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Turbulent flow is better than laminar flow to cool warm su..

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Anonymous
a b B Homebuilt system
June 13, 2004 5:58:37 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

Here are some interesting webpages that should convince
you that turbulent flow is better for cooling than laminar flow:

Let's start with a source a homebuider would
appreciate - http://www.overclockers.com/tips90/

A quote from the above webpage:

"Turbulent air cools better.
Say, for sake of argument, you have a simple tube
with a fan in the middle. The fan pulls air from
one side of the tube, and blows into the other.
If you have a hot component on the exhaust side
of the fan, it will be more efficiently cooled
than on the intake side. This is because the air
on the exhaust side of the fan is more turbulent.
For lack of a better explanation, the loops and
whorls of turbulent air moving across the surface
pick up more heat. The effective surface area of
the object is increased. (Actually, it was explained
to me by saying the effective surface area of the
air is increased.) The total volume of airflow
remains the same, but turbulent air just cools better."

If you want to pay more than $100 for a book or
monograph on heat transfer, you can find a multitude
of very academic books on turbulent flow and heat
transfer. Here's a blurb about one in the following
webpage -
http://www.begellhouse.com/books/497d60632054f587,6ddfe...

"Turbulent flow is the most common form of motion
of liquids and gases playing the role of the heat-
transfer medium in thermal systems. The complexity
of turbulent flow and the importance of hydrodynamics
and heat transfer in practice inspired continuing
research for methods of efficient heat augmentation
by the Lithuanian Energy Institute. The solution of
this problem was directly linked with the determination
of the reaction of flow in the boundary layer to the
effect of various factors and heat transfer rate under
given conditions. The investigated factors included
elevated degree of turbulence of the external flow as
well as strong acceleration and turbulization of flow
near the wall by surface roughness. The material in
this volume shows that it is possible to control the
efficiency of turbulent transfer when the vortical
structure of the turbulent flow is known."

You think this investigation of augmentation of
turbulent flow is to *reduce* heat transfer? I don't
think so. But read the book to be sure. :-)

And here's a nice little webpage -
http://www.cougarlabs.com/cool2.html . It's about
water cooling, but it applies to air cooling as well.
Here's a quote from it:

"Boundary Layers
When there is fluid flow across a surface, a velocity
boundary layer must develop. If the flow is in the
'laminar' flow regime, then the flow velocity in the
fluid at the surface is zero. A boundary layer is
formed, within which the shear stresses and velocity
gradients are large. At sufficient distance from the
surface, these same shear stresses and velocity gradients
become negligible."

"The problem, then, is this (simplistically): When
atoms/molecules strike the surface, they take on the
velocity of the surface (zero) and, to an extent, the
temperature of the surface. If these atoms/molecules
were to simply "get out of the way" to be replaced by
other (colder) atoms/molecules, then we could imagine
a great deal of heat being carried away."

"In addition to the velocity boundary layer, if there
is heat being carried away, then there must also be a
thermal boundary layer. Whereas the velocity boundary
layer was characterized by shear and velocity gradients,
the thermal boundary layer is characterized by temperature
gradients and heat transfer."

"Laminar, Transition and Turbulent
For convective heat transfer to work well, we need to
get the heat energy out into the flowing coolant.
Turbulence will do this for us."

"At low flow velocities, we can visualize 'streamlines'
along which the particles of the fluid actually move,
and transport is dominated by diffusion. However, as
the flow velocity becomes larger and larger, fluctuations
and irregularities will force the flow to become turbulent.
In between the extremes of laminar flow and turbulent flow,
we have a transition region where diffusion and turbulent
mixing are of about equal importance. Finally, in the
turbulent portion of the flow, transport is dominated by
turbulent mixing."


Need something more explicit? Try downloading this
..pdf document:
http://www.ceere.org/beep/docs/FY2002/Turbulent_Flow_in...

Here is a quote:

"In engineering applications, turbulence often displays apparent
differences from laminar flows. Comparatively speaking, turbulent
flows often lead to higher transport rate of momentum, energy and
mass than laminar flows. These features are widely made use of in
energy systems in industry. For example, turbulence enhancers such
as ribs are added to cooling systems of turbine blades and micro-
electronic devices to create more turbulent motions so that the
overall heat transfer efficiency can be improved."


There's a whole lot more, especially if you want to pay
for the information, but you get the idea -

Turbulent flow is better than laminar flow for cooling warm surfaces.

*TimDaniels*
Anonymous
a b B Homebuilt system
June 13, 2004 1:25:57 PM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"Timothy Daniels" <TDaniels@NoSpamDot.com> wrote in message
news:9LydnaPXg7OjilHd4p2dnA@comcast.com...
> Here are some interesting webpages that should convince
> you that turbulent flow is better for cooling than laminar flow:
snip

But this is totally irrelevant. There is no laminar airflow in a computer,
only turbulant.
Any air that gets moved by a fan will be turbulant, any air flowing over a
heatsink will be turbulant.
b
Anonymous
a b B Homebuilt system
June 13, 2004 7:50:58 PM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"Battleax" wrote:
>
> But this is totally irrelevant. There is no laminar airflow in a computer,
> only turbulant.
> Any air that gets moved by a fan will be turbulant, any air flowing over a
> heatsink will be turbulant.


You are thinking of a computer that has a fan blowing INTO it
at the front. Most PCs move air by an EXHAUST fan, and they
have no intake fan.
Most warm components have no dedicated fan, e.g. hard drive,
PCI boards, all non-CPU/GPU chips, resistors, diodes, etc.
These all need cooling, and turbulence improves the effect of
moving air.

*TimDaniels*
Related resources
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Anonymous
a b B Homebuilt system
June 13, 2004 9:41:06 PM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

On Sun, 13 Jun 2004 01:58:37 -0700, "Timothy Daniels"
<TDaniels@NoSpamDot.com> wrote:

>Here are some interesting webpages that should convince
>you that turbulent flow is better for cooling than laminar flow:
>

LOL, it's a new trend in usenet...
"I will win my argument by posting the same topic over and over again".
Anonymous
a b B Homebuilt system
June 13, 2004 9:41:07 PM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"kony" wrote:
> "Timothy Daniels"> wrote:
>
> >Here are some interesting webpages that should convince
> >you that turbulent flow is better for cooling than laminar flow:
> >
>
> LOL, it's a new trend in usenet...
> "I will win my argument by posting the same topic over and over again".


I won the argument where no one reads - at the bottom of a long thread.
This is for people who just read the top.

*TimDaniels*
Anonymous
a b B Homebuilt system
June 14, 2004 10:26:41 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

Timothy Daniels wrote:

> "Battleax" wrote:
>
>>But this is totally irrelevant. There is no laminar airflow in a computer,
>>only turbulant.
>>Any air that gets moved by a fan will be turbulant, any air flowing over a
>>heatsink will be turbulant.
>
>
>
> You are thinking of a computer that has a fan blowing INTO it
> at the front. Most PCs move air by an EXHAUST fan, and they
> have no intake fan.
> Most warm components have no dedicated fan, e.g. hard drive,
> PCI boards, all non-CPU/GPU chips, resistors, diodes, etc.
> These all need cooling, and turbulence improves the effect of
> moving air.
>
> *TimDaniels*

http://www.equipmentprotectionmagazine.com/eprints/UAF....

Air-Moving /Air-Straightening

..
..
..
Many ventilation systems generate turbulent flow at the inlet when air
rapidly enters the enclosure while being sliced by fan blades, then is
forced to turn sharp corners. This turbulence creates noise, slows the
airflow before exiting, and reduces effective cooling. Air straightening
decreases the vortices and input power, increases downstream velocity, and
maintains velocity over greater distances. This prevents large vortices
from forming and distributes the pressure drop more uniformly across the
chassis. The air filter media itself plays a major role in keeping airflow
laminar.
Anonymous
a b B Homebuilt system
June 14, 2004 10:40:54 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

Timothy Daniels wrote:

> "Battleax" wrote:
>
>>But this is totally irrelevant. There is no laminar airflow in a computer,
>>only turbulant.
>>Any air that gets moved by a fan will be turbulant, any air flowing over a
>>heatsink will be turbulant.
>
>
>
> You are thinking of a computer that has a fan blowing INTO it
> at the front. Most PCs move air by an EXHAUST fan, and they
> have no intake fan.
> Most warm components have no dedicated fan, e.g. hard drive,
> PCI boards, all non-CPU/GPU chips, resistors, diodes, etc.
> These all need cooling, and turbulence improves the effect of
> moving air.
>
> *TimDaniels*

http://64.233.161.104/search?q=cache:hJfM7Wv6A3cJ:www.n...

"Intake Or Exhaust?

Designers have the choice of mounting a fan to exhaust warm air from, or
blow cool air into, an enclosure. Theoretically, the same volume of air is
used to dissipate heat. However in real applications, each arrangement has
advantages and disadvantages. Air that is drawn into the fan flows
laminarly. Laminar flow allows for a uniformly distributed airflow velocity
in the enclosure. This is important in eliminating stagnant air and hot
spots. Air exhausted from the fan is turbulent. Heat dissipation in a
turbulent airflow can be up to double that of a laminar flow with the same
volumetric flow rate. But, the turbulent airflow region near a fan exhaust
is limited. Developing a well defined air flow path through the whole
enclosure is essential. Vents should be at least 50 percent larger in area
than the fan opening. Care must be taken to eliminate air recirculation in
a fan. Ninety percent, or more, of the airflow can be lost because of
recirculation problems. Baffles may be used to eliminate recirculation of
the same air. The airflow path will always take the path of least resistance."

---------------------------------
Note that since the downstream turbulent region created by an active fan
beating the hell out of the air is considered "limited" it's down right
minuscule for a passive vent hole.
Anonymous
a b B Homebuilt system
June 14, 2004 9:35:24 PM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"David Maynard" wrote:
> Timothy Daniels wrote:
>
> > "Battleax" wrote:
> >
> >>But this is totally irrelevant. There is no laminar airflow in a computer,
> >>only turbulant.
> >>Any air that gets moved by a fan will be turbulant, any air flowing over a
> >>heatsink will be turbulant.
> >
> >
> >
> > You are thinking of a computer that has a fan blowing INTO it
> > at the front. Most PCs move air by an EXHAUST fan, and they
> > have no intake fan.
> > Most warm components have no dedicated fan, e.g. hard drive,
> > PCI boards, all non-CPU/GPU chips, resistors, diodes, etc.
> > These all need cooling, and turbulence improves the effect of
> > moving air.
> >
> > *TimDaniels*
>
> http://www.equipmentprotectionmagazine.com/eprints/UAF....
>
> Air-Moving /Air-Straightening
>
> Many ventilation systems generate turbulent flow at the inlet when air
> rapidly enters the enclosure while being sliced by fan blades, then is
> forced to turn sharp corners. This turbulence creates noise, slows the
> airflow before exiting, and reduces effective cooling. Air straightening
> decreases the vortices and input power, increases downstream velocity, and
> maintains velocity over greater distances. This prevents large vortices
> from forming and distributes the pressure drop more uniformly across the
> chassis. The air filter media itself plays a major role in keeping airflow
> laminar.


That's definitely an argument for not using a fan to blow into the case
after the air that has already gone through a grating, isn't it?

*TimDaniels*
Anonymous
a b B Homebuilt system
June 14, 2004 9:43:50 PM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"David Maynard" wrote:
> Timothy Daniels wrote:
>
> > "Battleax" wrote:
> >
> >>But this is totally irrelevant. There is no laminar airflow in a computer,
> >>only turbulant.
> >>Any air that gets moved by a fan will be turbulant, any air flowing over a
> >>heatsink will be turbulant.
> >
> >
> >
> > You are thinking of a computer that has a fan blowing INTO it
> > at the front. Most PCs move air by an EXHAUST fan, and they
> > have no intake fan.
> > Most warm components have no dedicated fan, e.g. hard drive,
> > PCI boards, all non-CPU/GPU chips, resistors, diodes, etc.
> > These all need cooling, and turbulence improves the effect of
> > moving air.
> >
> > *TimDaniels*
>
>
http://64.233.161.104/search?q=cache:hJfM7Wv6A3cJ:www.n...
>
> "Intake Or Exhaust?
>
> Designers have the choice of mounting a fan to exhaust warm air from, or
> blow cool air into, an enclosure. Theoretically, the same volume of air is
> used to dissipate heat. However in real applications, each arrangement has
> advantages and disadvantages. Air that is drawn into the fan flows
> laminarly. Laminar flow allows for a uniformly distributed airflow velocity
> in the enclosure. This is important in eliminating stagnant air and hot
> spots. Air exhausted from the fan is turbulent. Heat dissipation in a
> turbulent airflow can be up to double that of a laminar flow with the same
> volumetric flow rate. But, the turbulent airflow region near a fan exhaust
> is limited. Developing a well defined air flow path through the whole
> enclosure is essential. Vents should be at least 50 percent larger in area
> than the fan opening. Care must be taken to eliminate air recirculation in
> a fan. Ninety percent, or more, of the airflow can be lost because of
> recirculation problems. Baffles may be used to eliminate recirculation of
> the same air. The airflow path will always take the path of least resistance."
>
> ---------------------------------
> Note that since the downstream turbulent region created by an active fan
> beating the hell out of the air is considered "limited" it's down right
> minuscule for a passive vent hole.


Air that has reached the exhaust fan will always be turbulent for many
reasons, not the least of which are the CPU fan, the GPU fan, and the
obstacle laden paths through the case. What must also be provided
with turbulent air flow are the components near the intake - the hard
drive(s) and upstream PCI cards. You can blow into the intake with
a fan (the noisy and costly way), or you can provide multiple holes
punched in the case (the quiet and cheap way).

*TimDaniels*
Anonymous
a b B Homebuilt system
June 15, 2004 3:43:54 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

Timothy Daniels wrote:

> "David Maynard" wrote:
>
>>Timothy Daniels wrote:
>>
>>
>>>"Battleax" wrote:
>>>
>>>
>>>>But this is totally irrelevant. There is no laminar airflow in a computer,
>>>>only turbulant.
>>>>Any air that gets moved by a fan will be turbulant, any air flowing over a
>>>>heatsink will be turbulant.
>>>
>>>
>>>
>>> You are thinking of a computer that has a fan blowing INTO it
>>> at the front. Most PCs move air by an EXHAUST fan, and they
>>> have no intake fan.
>>> Most warm components have no dedicated fan, e.g. hard drive,
>>> PCI boards, all non-CPU/GPU chips, resistors, diodes, etc.
>>> These all need cooling, and turbulence improves the effect of
>>> moving air.
>>>
>>>*TimDaniels*
>>
>>http://www.equipmentprotectionmagazine.com/eprints/UAF....
>>
>>Air-Moving /Air-Straightening
>>
>>Many ventilation systems generate turbulent flow at the inlet when air
>>rapidly enters the enclosure while being sliced by fan blades, then is
>>forced to turn sharp corners. This turbulence creates noise, slows the
>>airflow before exiting, and reduces effective cooling. Air straightening
>>decreases the vortices and input power, increases downstream velocity, and
>>maintains velocity over greater distances. This prevents large vortices
>>from forming and distributes the pressure drop more uniformly across the
>>chassis. The air filter media itself plays a major role in keeping airflow
>>laminar.
>
>
>
> That's definitely an argument for not using a fan to blow into the case
> after the air that has already gone through a grating, isn't it?

The point is that inlet 'turbulence' is not helpful, regardless of what
creates it.

Or, put in the inverse negative, as you seem to prefer, if one were trying
to induce inlet turbulence then a fan, especially eschewing those laminar
airflow filters they're trying to sell, would be a hell of a lot more
effective than any 'theory' regarding vent hole turbulence.




> *TimDaniels*
Anonymous
a b B Homebuilt system
June 15, 2004 3:43:55 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"David Maynard" wrote:
> The point is that inlet 'turbulence' is not helpful, regardless of what
> creates it.
>
> Or, put in the inverse negative, as you seem to prefer, if one were trying
> to induce inlet turbulence then a fan, especially eschewing those laminar
> airflow filters they're trying to sell, would be a hell of a lot more
> effective than any 'theory' regarding vent hole turbulence.


Tell it to Dell, Hewlett Packard, Gateway, etc. I'm sure they'd
welcome your secrets about inexpensive cooling methods.

*TimDaniels*
Anonymous
a b B Homebuilt system
June 15, 2004 3:51:35 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

Timothy Daniels wrote:

> "David Maynard" wrote:
>
>>Timothy Daniels wrote:
>>
>>
>>>"Battleax" wrote:
>>>
>>>
>>>>But this is totally irrelevant. There is no laminar airflow in a computer,
>>>>only turbulant.
>>>>Any air that gets moved by a fan will be turbulant, any air flowing over a
>>>>heatsink will be turbulant.
>>>
>>>
>>>
>>> You are thinking of a computer that has a fan blowing INTO it
>>> at the front. Most PCs move air by an EXHAUST fan, and they
>>> have no intake fan.
>>> Most warm components have no dedicated fan, e.g. hard drive,
>>> PCI boards, all non-CPU/GPU chips, resistors, diodes, etc.
>>> These all need cooling, and turbulence improves the effect of
>>> moving air.
>>>
>>>*TimDaniels*
>>
>>
> http://64.233.161.104/search?q=cache:hJfM7Wv6A3cJ:www.n...
>
>>"Intake Or Exhaust?
>>
>>Designers have the choice of mounting a fan to exhaust warm air from, or
>>blow cool air into, an enclosure. Theoretically, the same volume of air is
>>used to dissipate heat. However in real applications, each arrangement has
>>advantages and disadvantages. Air that is drawn into the fan flows
>>laminarly. Laminar flow allows for a uniformly distributed airflow velocity
>>in the enclosure. This is important in eliminating stagnant air and hot
>>spots. Air exhausted from the fan is turbulent. Heat dissipation in a
>>turbulent airflow can be up to double that of a laminar flow with the same
>>volumetric flow rate. But, the turbulent airflow region near a fan exhaust
>>is limited. Developing a well defined air flow path through the whole
>>enclosure is essential. Vents should be at least 50 percent larger in area
>>than the fan opening. Care must be taken to eliminate air recirculation in
>>a fan. Ninety percent, or more, of the airflow can be lost because of
>>recirculation problems. Baffles may be used to eliminate recirculation of
>>the same air. The airflow path will always take the path of least resistance."
>>
>>---------------------------------
>>Note that since the downstream turbulent region created by an active fan
>>beating the hell out of the air is considered "limited" it's down right
>>minuscule for a passive vent hole.
>
>
>
> Air that has reached the exhaust fan will always be turbulent for many
> reasons, not the least of which are the CPU fan, the GPU fan, and the
> obstacle laden paths through the case. What must also be provided
> with turbulent air flow are the components near the intake - the hard
> drive(s) and upstream PCI cards. You can blow into the intake with
> a fan (the noisy and costly way), or you can provide multiple holes
> punched in the case (the quiet and cheap way).

The whole POINT is that inlet 'turbulence' is USELESS and only serves to
reduce the airflow.


>
> *TimDaniels*
>
Anonymous
a b B Homebuilt system
June 15, 2004 3:51:36 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"David Maynard" wrote:
> The whole POINT is that inlet 'turbulence' is USELESS
> and only serves to reduce the airflow.


OK, we'll have to start from the beginning, again.
Start with these:
http://www.overclockers.com/tips90/
http://www.begellhouse.com/books/497d60632054f587,6ddfe...
http://www.cougarlabs.com/cool2.html
http://www.ceere.org/beep/docs/FY2002/Turbulent_Flow_in...


The conclusions: Turbulence aids the transfer of heat between
a surface and the fluid flowing over it.

*TimDaniels*
Anonymous
a b B Homebuilt system
June 15, 2004 6:35:21 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

On Mon, 14 Jun 2004 17:35:24 -0700, "Timothy Daniels"
<TDaniels@NoSpamDot.com> wrote:

>"David Maynard" wrote:
>> Timothy Daniels wrote:
>>
>> > "Battleax" wrote:
>> >
>> >>But this is totally irrelevant. There is no laminar airflow in a computer,
>> >>only turbulant.
>> >>Any air that gets moved by a fan will be turbulant, any air flowing over a
>> >>heatsink will be turbulant.
>> >
>> >
>> >
>> > You are thinking of a computer that has a fan blowing INTO it
>> > at the front. Most PCs move air by an EXHAUST fan, and they
>> > have no intake fan.
>> > Most warm components have no dedicated fan, e.g. hard drive,
>> > PCI boards, all non-CPU/GPU chips, resistors, diodes, etc.
>> > These all need cooling, and turbulence improves the effect of
>> > moving air.
>> >
>> > *TimDaniels*
>>
>> http://www.equipmentprotectionmagazine.com/eprints/UAF....
>>
>> Air-Moving /Air-Straightening
>>
>> Many ventilation systems generate turbulent flow at the inlet when air
>> rapidly enters the enclosure while being sliced by fan blades, then is
>> forced to turn sharp corners. This turbulence creates noise, slows the
>> airflow before exiting, and reduces effective cooling. Air straightening
>> decreases the vortices and input power, increases downstream velocity, and
>> maintains velocity over greater distances. This prevents large vortices
>> from forming and distributes the pressure drop more uniformly across the
>> chassis. The air filter media itself plays a major role in keeping airflow
>> laminar.
>
>
> That's definitely an argument for not using a fan to blow into the case
> after the air that has already gone through a grating, isn't it?
>
>*TimDaniels*

LOL, no, it's an argument that if there wasn't a fan then the ventilation
system wouldn't move the air at all, and that the goal is maintaining
needed flow rate with minimal noise ratio. In other words, minimize the
impedance to flow, not be elimination of the fan but of passive obstacles.
The filter is an exception, since it keeps system clean and enviroment
hospitable.
Anonymous
a b B Homebuilt system
June 15, 2004 7:13:00 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

Timothy Daniels wrote:

> "David Maynard" wrote:
>
>>The point is that inlet 'turbulence' is not helpful, regardless of what
>>creates it.
>>
>>Or, put in the inverse negative, as you seem to prefer, if one were trying
>>to induce inlet turbulence then a fan, especially eschewing those laminar
>>airflow filters they're trying to sell, would be a hell of a lot more
>>effective than any 'theory' regarding vent hole turbulence.
>
>
>
> Tell it to Dell, Hewlett Packard, Gateway, etc. I'm sure they'd
> welcome your secrets about inexpensive cooling methods.

No one needs to "tell it to Dell, Hewlett Packard, Gateway, etc." because
they already know how to design proper airflow, and your 'vent hole
turbulence' theory ain't a part of it.

All you're doing by ignoring the literature is proving my analogy about how
you'd be still claiming the Pacific Ocean is a sand desert even after
having your head shoved into it.
Anonymous
a b B Homebuilt system
June 15, 2004 7:29:23 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

Timothy Daniels wrote:

> "David Maynard" wrote:
>
>>The whole POINT is that inlet 'turbulence' is USELESS
>>and only serves to reduce the airflow.
>
>
>
> OK, we'll have to start from the beginning, again.
> Start with these:
> http://www.overclockers.com/tips90/
> http://www.begellhouse.com/books/497d60632054f587,6ddfe...
> http://www.cougarlabs.com/cool2.html
> http://www.ceere.org/beep/docs/FY2002/Turbulent_Flow_in...
>
>
> The conclusions: Turbulence aids the transfer of heat between
> a surface and the fluid flowing over it.
>
> *TimDaniels*
>

Get this through your thick head: The turbulence created by 'vent holes'
doesn't extend into the case far enough to cool a damn thing other than the
stupid vent holes, and none of your articles say otherwise. So if you're
all fired worried about 'hot' vent holes then, by all means, drill a ton of
them.

If, however, you're concerned with cooling other things, like the CPU,
motherboard components, and hard drives then you're going to have to find
some other means for creating the desired turbulence THERE, where the heat is.

Of course, you first have to get air TO them, before you can expect
turbulence THERE, and the stupid vent holes are a flow restriction but,
unfortunately, they're the cheapest EMI shielding solution.
Anonymous
a b B Homebuilt system
June 15, 2004 3:20:34 PM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"David Maynard" wrote:
> No one needs to "tell it to Dell, Hewlett Packard, Gateway, etc."
> because they already know how to design proper airflow, and
> your 'vent hole turbulence' theory ain't a part of it.


Then why do they use multiple holes instead of a wire grill
at their air intakes? One big hole with a wire grill would flow
more air and block EMI, but would produce less turbulence
than the holes. But yet they use the multiple holes of various
sizes and a plastic fascia to cover them - which requires
the incoming air to make right angle turn - just the thing to
cause turbulence. Educated engineers designed this. I
wonder why?


> All you're doing by ignoring the literature....


What literature?

*TimDaniels*
Anonymous
a b B Homebuilt system
June 15, 2004 3:43:06 PM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"David Maynard" goes 'round the bend:
> Get this through your thick head: The turbulence created by 'vent holes'
> doesn't extend into the case far enough to cool a damn thing other than the
> stupid vent holes, and none of your articles say otherwise. So if you're
> all fired worried about 'hot' vent holes then, by all means, drill a ton of
> them.


Why a ton? A dozen should suffice.


> If, however, you're concerned with cooling other things, like the CPU,
> motherboard components, and hard drives then you're going to have to find
> some other means for creating the desired turbulence THERE, where the heat is.


And why ignore the hard drive(s)? Are they unimportant? How about
the PCI cards? Don't they have chips that need cooling, too? And
unless you have a motherboard that has a dedicated shrouded fan,
it needs turbulence as well to scrub down among the surface-mounted
components. For some reason, you think that turbulence generated
at the intake somehow dissipates in the one or two seconds that it
takes to get to the motherboard, and that only laminar flow exists
at that point. Like I said in another thread, that's the molasses theory
of air flow - i.e. the belief that air has the same degree of viscosity
as that of molasses. But air is *not* as viscous as molasses, and
turbulence *does* last - certainly longer than the time that it takes
to transit the interior of a PC case. But... it's not as easy to measure
or discern as turbulence, and one who has built up a belief in the
insignificance of turbulence would certainly dismiss it.


> Of course, you first have to get air TO them, before you can expect
> turbulence THERE, and the stupid vent holes are a flow restriction but,
> unfortunately, they're the cheapest EMI shielding solution.


Cheaper would be one big hole with a wire grill instead of multiple
punched holes and a complex plastic fascia. Yet the big manufacturers
who can afford to do cut-'n-try design work and who can afford to
hire real college-educated engineers go with multiple holes and the
complex fascia. Hmmm... maybe they know something the homebrew
crowd doesn't know...

*TimDaniels*
Anonymous
a b B Homebuilt system
June 15, 2004 5:00:55 PM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

On Mon, 14 Jun 2004 23:34:28 -0700, "Timothy Daniels"
<TDaniels@NoSpamDot.com> wrote:

>"David Maynard" wrote:
>> The point is that inlet 'turbulence' is not helpful, regardless of what
>> creates it.
>>
>> Or, put in the inverse negative, as you seem to prefer, if one were trying
>> to induce inlet turbulence then a fan, especially eschewing those laminar
>> airflow filters they're trying to sell, would be a hell of a lot more
>> effective than any 'theory' regarding vent hole turbulence.
>
>
> Tell it to Dell, Hewlett Packard, Gateway, etc. I'm sure they'd
> welcome your secrets about inexpensive cooling methods.
>
>*TimDaniels*

"Inexpensive" being the key word here... it's not that it's better, just
simplier and cheaper. They do not increase the complexity or cost when it
isn't necessary to keep the system operational as-shipped.
Anonymous
a b B Homebuilt system
June 15, 2004 5:00:56 PM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"kony"
> > Tell it to Dell, Hewlett Packard, Gateway, etc. I'm sure
> > they'd welcome your secrets about inexpensive cooling
> > methods.
> >
> >*TimDaniels*
>
> "Inexpensive" being the key word here... it's not that it's better,
> just simplier and cheaper. They do not increase the complexity
> or cost when it isn't necessary to keep the system operational
> as-shipped.


And why do they go to the trouble of making holes big enough
to stick a finger or pen into and then add a plastic fascia to keep
those fingers and pens out? Why don't they put a wire grill over
one big hole? Maybe because the holes and the fascia make
for real nice intake turbulence?

*TimDaniels*
Anonymous
a b B Homebuilt system
June 15, 2004 10:31:39 PM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"Timothy Daniels" <TDaniels@NoSpamDot.com> wrote in message
news:rf-dneVZS49poFLdRVn-uQ@comcast.com...
>
> Then why do they use multiple holes instead of a wire grill
> at their air intakes? One big hole with a wire grill would flow
> more air and block EMI, but would produce less turbulence
> than the holes. But yet they use the multiple holes of various
> sizes and a plastic fascia to cover them - which requires
> the incoming air to make right angle turn - just the thing to
> cause turbulence. Educated engineers designed this. I
> wonder why?

Because it's a lot cheaper to punch holes than to make a seprate screen and
attach it.
Anonymous
a b B Homebuilt system
June 15, 2004 10:31:40 PM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"Battleax" offered:
> Because it's a lot cheaper to punch holes than to make
> a seprate screen and attach it.


And the fancy 3-dimensional molded fascia? Is
that cheap to make and attach, too? It wouldn't be
needed with a wire grill over just one big hole...

*TimDaniels*
Anonymous
a b B Homebuilt system
June 16, 2004 3:04:23 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

Timothy Daniels wrote:

> "David Maynard" wrote:
>
>>No one needs to "tell it to Dell, Hewlett Packard, Gateway, etc."
>>because they already know how to design proper airflow, and
>>your 'vent hole turbulence' theory ain't a part of it.
>
>
>
> Then why do they use multiple holes instead of a wire grill
> at their air intakes?

I already told you why, and posted the EMI specs to prove it.

> One big hole with a wire grill would flow
> more air and block EMI,

It costs more.

> but would produce less turbulence
> than the holes. But yet they use the multiple holes of various
> sizes and a plastic fascia to cover them - which requires
> the incoming air to make right angle turn - just the thing to
> cause turbulence. Educated engineers designed this. I
> wonder why?

Because it's the least costly solution that's sufficient to the task.


>>All you're doing by ignoring the literature....
>
>
>
> What literature?

The literature I've posted, that you keep snipping out, because it
contradicts your 'religion' of 'vent hole turbulence'.

>
> *TimDaniels*
Anonymous
a b B Homebuilt system
June 16, 2004 3:23:37 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

On Tue, 15 Jun 2004 11:26:49 -0700, "Timothy Daniels"
<TDaniels@NoSpamDot.com> wrote:

>"kony"
>> > Tell it to Dell, Hewlett Packard, Gateway, etc. I'm sure
>> > they'd welcome your secrets about inexpensive cooling
>> > methods.
>> >
>> >*TimDaniels*
>>
>> "Inexpensive" being the key word here... it's not that it's better,
>> just simplier and cheaper. They do not increase the complexity
>> or cost when it isn't necessary to keep the system operational
>> as-shipped.
>
>
> And why do they go to the trouble of making holes big enough
> to stick a finger or pen into and then add a plastic fascia to keep
> those fingers and pens out?

That's just it, they don't "go to the trouble of...".
They just use same simple, time-proven design and minimal parts as always,
and follow Intel & AMD guidelines. Those guidelines include power supply,
rear case fan, but not vent hole turbulence.

Additionally, if that "holes big enough to stick a finger or pen into" was
their idea of good turbulence, they why don't they make all of their cases
with similar hole size? Many OEM cases do not have holes large enough to
put a finger or pen in, but some do... There is no optimization towards
hole turbulence. In fact, many OEM cases were simply selected from
designs of case manufacturers with custom faceplates, a duct on power
supply or rear fan, etc... no frame changes, just "snap on" parts added.

> Why don't they put a wire grill over
> one big hole? Maybe because the holes and the fascia make
> for real nice intake turbulence?

Why don't they put a NiMH battery changer on the front of every case or a
neon dancing turtle on top?
Because there isn't enough demand for that either.

Even intel, in their revised BTX design guide, has specifically mentioned
moving away from the age-old passive-hole design.

"the air channel and chassis vent should be designed so that there is
minimal impedance to airflow from outside the chassis to the defined
interface." (Section 3.3.3).

They spent a fair amount of time testing that, are they completely wrong
too?

If you want to believe your hole theory, so be it. I'm perfectly happy
letting you believe you have optimal cooling... if you do end up having
problems you might want to rethink your theory. That's all the time I
care to spend on case holes, no need for another long thread like the last
one.
Anonymous
a b B Homebuilt system
June 16, 2004 3:23:38 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"kony" wrote:
> "Timothy Daniels" wrote:
> > And why do they go to the trouble of making holes
> > big enough to stick a finger or pen into and then
> > add a plastic fascia to keep those fingers and pens out?
>
> That's just it, they don't "go to the trouble of...".
> They just use same simple, time-proven design and minimal
> parts as always, and follow Intel & AMD guidelines.


The complex and distinctive fascias on the various name
brand PCs are "simple", "time-proven" and "minimal"?
Does Intel and AMD really design these in secret and
sell them to Dell, HP, Gateway and the rest? Of course
not! They are products of engineering experimentation
and design, and not just to keep fingers out.


> Those guidelines include power supply,
> rear case fan, but not vent hole turbulence.


So? Do you think for a moment that Dell, HP, Gateway,
et. al. depend on Intel and AMD to tell them how to
design their cases so that Intel's and AMD's components
get adequately cooled? Intel's and AMD's "guidelines"
are for homebuilders who don't have the facilities to
experiment with turbulence generating structures. It's
quite probably the case that Dell, HP, Gateway, et. al.
know *more* about providing adequate cooling at low
cost than does Intel and AMD because that is what
Dell, HP, Gateway, et. al. *do* for a living, while Intel and
AMD make *their* living by designing and manufacturing chips.



> Additionally, if that "holes big enough to stick a finger
> or pen into" was their idea of good turbulence, they why
> don't they make all of their cases with similar hole size?


That's because different size holes produce different size
vortices and air flow. Remember "cut-'n-try"? Each
PC model's interior is different from that of other models,
and thus their air flow and turbulence needs are different.


> Even intel, in their revised BTX design guide, has specifically
> mentioned moving away from the age-old passive-hole design.


Great. They get their turbulence from intake fans. It's costlier,
but it increases air flow by putting fans in series and the smaller
form factor demands a smaller fan than can be put on the back
of a BTX case. For BTX, it makes sense.


> "the air channel and chassis vent should be designed so that there is
> minimal impedance to airflow from outside the chassis to the defined
> interface." (Section 3.3.3).


Since there is no a priori way to specify a degree of turbulence,
especially to a homebuilder, they deal only with air flow rate.
What alternative do they have? Would you appreciate advice
to set up a cooling lab to experiment with size and number and
placement of intake holes? Unless you have the budget of Dell,
HP, Gateway, et. al., all you can deal with is how big a fan
you might need.


> They spent a fair amount of time testing that, are they completely
> wrong too?


How could the writer(s) of such a guideline specify how to
generate the optimal degree of turbulence? The most that
they could specify in a set of "guidelines" is to "flow as much
air as you can, dude". And so simple bulk air flow is thrown
at the problem like a blunt object. Great. It gets the job done -
but at the expense of a bigger fan, a faster fan, or even *more*
fans, and with the expense of greater noise.

*TimDaniels*
Anonymous
a b B Homebuilt system
June 16, 2004 3:36:43 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

Timothy Daniels wrote:

> "David Maynard" goes 'round the bend:
>
>>Get this through your thick head: The turbulence created by 'vent holes'
>>doesn't extend into the case far enough to cool a damn thing other than the
>>stupid vent holes, and none of your articles say otherwise. So if you're
>>all fired worried about 'hot' vent holes then, by all means, drill a ton of
>>them.
>
>
>
> Why a ton? A dozen should suffice.

The euphemism 'a ton' was based on your non-numerical method of universal
extrapolation that if it works 'somewhere' in 'some manner' then it must be
God's answer to every unexplained question and universally applicable no
matter what.


>>If, however, you're concerned with cooling other things, like the CPU,
>>motherboard components, and hard drives then you're going to have to find
>>some other means for creating the desired turbulence THERE, where the heat is.
>
>
>
> And why ignore the hard drive(s)? Are they unimportant? How about
> the PCI cards? Don't they have chips that need cooling, too?

You don't even read.

> And
> unless you have a motherboard that has a dedicated shrouded fan,
> it needs turbulence as well to scrub down among the surface-mounted
> components.

One doesn't need a "shrouded fan" to create turbulence.

> For some reason, you think that turbulence generated
> at the intake somehow dissipates in the one or two seconds that it
> takes to get to the motherboard,

I never said a thing about 'seconds'. I stated it in distance, and the
turbulence created by 'vent holes' is located at the vent holes.

And, consistent with your question, what the hell makes you think 'vent
hole turbulence' persists for any significant distance and where's your
proof of it?


> and that only laminar flow exists
> at that point.

I also never said a blessed thing about "only laminar flow exists."


> Like I said in another thread, that's the molasses theory
> of air flow - i.e. the belief that air has the same degree of viscosity
> as that of molasses.

You've said a lot of things that are flat wrong and this type of 'straw
man' argument seems to be your second favorite illogic, right after
'universal extrapolation'.

> But air is *not* as viscous as molasses,

Another straw man as no one ever said it was.

> and
> turbulence *does* last - certainly longer than the time that it takes
> to transit the interior of a PC case.

And your proof of this is where?

> But... it's not as easy to measure
> or discern as turbulence,

So you believe in immeasurable and indiscernible things?

> and one who has built up a belief in the
> insignificance of turbulence would certainly dismiss it.

And another straw man as I never said a thing about turbulence being
'insignificant'.

>>Of course, you first have to get air TO them, before you can expect
>>turbulence THERE, and the stupid vent holes are a flow restriction but,
>>unfortunately, they're the cheapest EMI shielding solution.
>
>
>
> Cheaper would be one big hole with a wire grill

No, it costs more.

> instead of multiple
> punched holes and a complex plastic fascia.

There is nothing about the punched holes that 'requires' or 'needs' a
"complex plastic fascia."

> Yet the big manufacturers
> who can afford to do cut-'n-try design work

This notion of "cut-'n-try design work" is another of your fantasies.

> and who can afford to
> hire real college-educated engineers go with multiple holes and the
> complex fascia. Hmmm... maybe they know something the homebrew
> crowd doesn't know...

Yeah, for one, they know that adding unneeded cost to every case is a waste.

>
> *TimDaniels*
>
Anonymous
a b B Homebuilt system
June 16, 2004 3:44:26 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

Timothy Daniels wrote:

> "Battleax" offered:
>
>>Because it's a lot cheaper to punch holes than to make
>>a seprate screen and attach it.
>
>
>
> And the fancy 3-dimensional molded fascia?

Its for 'pretty'.

> Is
> that cheap to make and attach, too?

Once the mold is made the shape has little impact on cost. You pop it out
and screw it on. In fact, that's how the 'many different case styles' are
done: one common chassis with a bevy of different molded fascias that all
attach to it the same way.

> It wouldn't be
> needed with a wire grill over just one big hole...

There's nothing about vent holes that 'requires' or 'needs' a complex fascia.


>
> *TimDaniels*
Anonymous
a b B Homebuilt system
June 16, 2004 3:44:27 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"David Maynard" wrote:
> There's nothing about vent holes that 'requires'
> or 'needs' a complex fascia.


Unless you want to cause a right angle turn
in the air flow. There is no reason the turn
must be a right angle to keep out fingers
and pens. But the right angle sure makes
some fine turbulence.

*TimDaniels*
Anonymous
a b B Homebuilt system
June 16, 2004 3:45:33 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"David Maynard" wrote:
> Timothy Daniels wrote:
> > Then why do they use multiple holes instead of a wire grill
> > at their air intakes?
>
> I already told you why, and posted the EMI specs to prove it.


Nonsense. You posted specs for a maximum acceptable
level of EMI, not how to achieve it. That you think holes
are to contain the EMI is *your* giant leap of faith.


> > One big hole with a wire grill would flow
> > more air and block EMI,
>
> It costs more.


A wire grill snapped over a big hole
is more expensive than a fancy 3-dimensional
molded tight-tolerance plastic fascia and the
hardware to attach it?



> > but would produce less turbulence
> > than the holes. But yet they use the multiple holes of various
> > sizes and a plastic fascia to cover them - which requires
> > the incoming air to make right angle turn - just the thing to
> > cause turbulence. Educated engineers designed this. I
> > wonder why?
>
> Because it's the least costly solution that's sufficient to the task.


A wire grill snapped over a big hole
is more expensive than a fancy 3-dimensional
molded tight-tolerance plastic fascia and the
hardware to attach it?


> > What literature?
>
> The literature I've posted, that you keep snipping out, because it
> contradicts your 'religion' of 'vent hole turbulence'.


What literature?
Post a link and explain what it says and why it's relevant.

*TimDaniels*
Anonymous
a b B Homebuilt system
June 16, 2004 3:53:09 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

Timothy Daniels wrote:

> "kony" wrote:
>
>>"Timothy Daniels" wrote:
>>
>>> And why do they go to the trouble of making holes
>>> big enough to stick a finger or pen into and then
>>> add a plastic fascia to keep those fingers and pens out?
>>
>>That's just it, they don't "go to the trouble of...".
>>They just use same simple, time-proven design and minimal
>>parts as always, and follow Intel & AMD guidelines.
>
>
>
> The complex and distinctive fascias on the various name
> brand PCs are "simple", "time-proven" and "minimal"?
> Does Intel and AMD really design these in secret and
> sell them to Dell, HP, Gateway and the rest? Of course
> not! They are products of engineering experimentation
> and design, and not just to keep fingers out.

Horse hockey. They're the products of art design.


>>Those guidelines include power supply,
>>rear case fan, but not vent hole turbulence.
>
>
>
> So? Do you think for a moment that Dell, HP, Gateway,
> et. al. depend on Intel and AMD to tell them how to
> design their cases so that Intel's and AMD's components
> get adequately cooled? Intel's and AMD's "guidelines"
> are for homebuilders who don't have the facilities to
> experiment with turbulence generating structures. It's
> quite probably the case that Dell, HP, Gateway, et. al.
> know *more* about providing adequate cooling at low
> cost than does Intel and AMD because that is what
> Dell, HP, Gateway, et. al. *do* for a living, while Intel and
> AMD make *their* living by designing and manufacturing chips.

This is proof positive that you have no idea of what you speak and are just
making up things to suit your fancy.

The first rule of good engineering is "don't reinvent the wheel" and damn
right they pay attention to Intel and AMD specs and guidelines.


>>Additionally, if that "holes big enough to stick a finger
>>or pen into" was their idea of good turbulence, they why
>>don't they make all of their cases with similar hole size?
>
>
>
> That's because different size holes produce different size
> vortices and air flow. Remember "cut-'n-try"?

I'm sure he remembers your fanciful invention of "cut-'n-try.".


> Each
> PC model's interior is different from that of other models,
> and thus their air flow and turbulence needs are different.

And "engineering" is the process of applying knowledge to design, not
"cut-'n'try."


<snip of more Tim 'guessing' how designers design things>
Anonymous
a b B Homebuilt system
June 16, 2004 3:53:10 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"David Maynard" wrote:
> Timothy Daniels wrote:
> > The complex and distinctive fascias on the various name
> > brand PCs are "simple", "time-proven" and "minimal"?
> > Does Intel and AMD really design these in secret and
> > sell them to Dell, HP, Gateway and the rest? Of course
> > not! They are products of engineering experimentation
> > and design, and not just to keep fingers out.
>
> Horse hockey. They're the products of art design.


And in good design, form follows function. That the
function happens to involve making turbulence is just
accidental, I suppose?



> This is proof positive that you have no idea of what you speak
> and are just making up things to suit your fancy.
>
> The first rule of good engineering is "don't reinvent the wheel"
> and damn right they pay attention to Intel and AMD specs and
> guidelines.


And why are Intel and AMD engineers superior to Dell's,
HP's, and Gateway's engineers in case cooling design?
I thought Intel and AMD were in the chip business.

*TimDaniels*
Anonymous
a b B Homebuilt system
June 16, 2004 4:18:14 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"David Maynard" wrote:
> Timothy Daniels wrote:
> > For some reason, you think that turbulence generated
> > at the intake somehow dissipates in the one or two
> > seconds that it takes to get to the motherboard,
>
> I never said a thing about 'seconds'. I stated it in distance,
> and the turbulence created by 'vent holes' is located at the
> vent holes.


Just how long, then, is the distance from the air intake
to the hard drive? One inch? Two inches? How much
time do you think it takes for the air to travel that
distance? Half a second? One second? However much
time it takes, you believe that air turbulence will die out
in that length of time. That has got to be the Molasses
Theory of fluid flow.


> And, consistent with your question, what the hell makes
> you think 'vent hole turbulence' persists for any significant
> distance and where's your proof of it?


Blow into a cloud of smoke and watch how long it
takes for the turbulence to dissipate.


> > and that only laminar flow exists
> > at that point.
>
> I also never said a blessed thing about "only laminar flow exists."


If the air is not turbulent, it must be laminar - unless your
Molasses Theory of fluid flow has some 3rd kinetic
state of fluid.


> > and turbulence *does* last - certainly longer
> > than the time that it takes to transit the interior
> > of a PC case.
>
> And your proof of this is where?


Blow into a cloud of smoke and watch how long it
takes for the turbulence to dissipate.


> > But... it's not as easy to measure
> > or discern as turbulence,
>
> So you believe in immeasurable and indiscernible things?


Turbulence is extremely hard to even specify,
much less measure and model. But it is very
easy to see - outside a case. Unless you're viewing
smoke trails inside a case with a fiberoptic probe,
discerning the path of turbulence is very difficult,
outside the capabilities of a homebuilder certainly.
What *is* easy is to believe the CFM specs of fan
manufacturers and to then believe how much
"air flow" there is through a case - with no
consideration for the degree of turbulence. "Air flow"
is easy to believe in as a direct measure of heat
transfer because it's so simple to measure.
Turbulence, on the other hand, is hard to measure.
Just too begin with, what units do you use?
But scientific researchers publish reports to show
that turbulence has a definite effect on heat transfer
between a moving fluid and an adjacent surface,
and to ignore that by saying "It's irrelevant. It dies
out soon after it's generated." is to deny why one
swipe with your spoon will continue to stir your
coffee or why walking through a smoke-filled
room will leave the smoke swirling for a minute.

*TimDaniels*
Anonymous
a b B Homebuilt system
June 16, 2004 4:53:46 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

On Tue, 15 Jun 2004 16:38:34 -0700, "Timothy Daniels"
<TDaniels@NoSpamDot.com> wrote:

>
>"Battleax" offered:
>> Because it's a lot cheaper to punch holes than to make
>> a seprate screen and attach it.
>
>
> And the fancy 3-dimensional molded fascia? Is
> that cheap to make and attach, too? It wouldn't be
> needed with a wire grill over just one big hole...
>
>*TimDaniels*

You really think any of the OEMs would sell PCs without the molded fascia
regardless of what the metal sheeting was like behind it?

It's called aesthetics.
Anonymous
a b B Homebuilt system
June 16, 2004 4:53:47 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"kony" wrote:
> You really think any of the OEMs would sell PCs
> without the molded fascia regardless of what the
> metal sheeting was like behind it?
>
> It's called aesthetics.


No, it's called cooling design. The sheet metal
benders like Antec certainly sell their do-it-yourself
cases to guys like you without plastic fascias. That's
because you'll buy their fans to make the turbulence
to bring down the temps in those cases. Dell and
HP and Gateway don't like buying fans.

*TimDaniels*
Anonymous
a b B Homebuilt system
June 16, 2004 11:08:37 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

Timothy Daniels wrote:

> "David Maynard" wrote:
>
>>There's nothing about vent holes that 'requires'
>>or 'needs' a complex fascia.
>
>
>
> Unless you want to cause a right angle turn
> in the air flow. There is no reason the turn
> must be a right angle to keep out fingers
> and pens. But the right angle sure makes
> some fine turbulence.

There is no 'desire' to have it make a 'right angle turn'; they end up
doing it because a lot of people think it's friggin PRETTIER to not have
the damn holes on the case front and there has to be a hole SOME where, so
it ends up at the front bottom edge.


>
> *TimDaniels*
Anonymous
a b B Homebuilt system
June 16, 2004 11:19:10 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

Timothy Daniels wrote:

> "David Maynard" wrote:
>
>>Timothy Daniels wrote:
>>
>>> The complex and distinctive fascias on the various name
>>> brand PCs are "simple", "time-proven" and "minimal"?
>>> Does Intel and AMD really design these in secret and
>>> sell them to Dell, HP, Gateway and the rest? Of course
>>> not! They are products of engineering experimentation
>>> and design, and not just to keep fingers out.
>>
>>Horse hockey. They're the products of art design.
>
>
>
> And in good design, form follows function. That the
> function happens to involve making turbulence is just
> accidental, I suppose?

As usual, you 'suppose' wrongly.

>
>>This is proof positive that you have no idea of what you speak
>>and are just making up things to suit your fancy.
>>
>>The first rule of good engineering is "don't reinvent the wheel"
>>and damn right they pay attention to Intel and AMD specs and
>>guidelines.
>
>
> And why are Intel and AMD engineers superior to Dell's,
> HP's, and Gateway's engineers in case cooling design?
> I thought Intel and AMD were in the chip business.

Another straw man as no one said a thing about one or the other being
'superior'.
Anonymous
a b B Homebuilt system
June 16, 2004 11:36:42 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

Timothy Daniels wrote:

> "David Maynard" wrote:
>
>>Timothy Daniels wrote:
>>
>>> For some reason, you think that turbulence generated
>>> at the intake somehow dissipates in the one or two
>>> seconds that it takes to get to the motherboard,
>>
>>I never said a thing about 'seconds'. I stated it in distance,
>>and the turbulence created by 'vent holes' is located at the
>>vent holes.
>
>
>
> Just how long, then, is the distance from the air intake
> to the hard drive? One inch? Two inches? How much
> time do you think it takes for the air to travel that
> distance? Half a second? One second? However much
> time it takes, you believe that air turbulence will die out
> in that length of time. That has got to be the Molasses
> Theory of fluid flow.

What you think 'has to be' is meaningless.


>>And, consistent with your question, what the hell makes
>>you think 'vent hole turbulence' persists for any significant
>>distance and where's your proof of it?
>
> Blow into a cloud of smoke and watch how long it
> takes for the turbulence to dissipate.

Meaningless as there's no constant airflow in my room.


>>>and that only laminar flow exists
>>> at that point.
>>
>>I also never said a blessed thing about "only laminar flow exists."
>
>
>
> If the air is not turbulent, it must be laminar - unless your
> Molasses Theory of fluid flow has some 3rd kinetic
> state of fluid.

Logic isn't your strong suit. The issue is whether the 'vent holes' create
useful turbulence or something else and not that it's 'laminar' throughout
the case unless your magical vent holes save us from impending thermal doom.


>>> and turbulence *does* last - certainly longer
>>> than the time that it takes to transit the interior
>>> of a PC case.
>>
>>And your proof of this is where?
>
> Blow into a cloud of smoke and watch how long it
> takes for the turbulence to dissipate.

I tried that but the heatsink didn't get any cooler.

>
>>> But... it's not as easy to measure
>>> or discern as turbulence,
>>
>>So you believe in immeasurable and indiscernible things?
>
> Turbulence is extremely hard to even specify,
> much less measure and model. But it is very
> easy to see - outside a case.

You can 'see' lots of things but that doesn't mean you can universally
extrapolate it to just any old damn thing you feel like. e.g. a 'feather'
floats gently to the ground but that doesn't mean I can make a 50 foot
'feather' out of lead and have it float gently to the ground.

> Unless you're viewing
> smoke trails inside a case with a fiberoptic probe,
> discerning the path of turbulence is very difficult,
> outside the capabilities of a homebuilder certainly.

Don't need to. Just cut out the holes and watch the temperatures skyrocket
because your magical vent holes are gone.

It won't, of course, but that wouldn't stop you either.

> What *is* easy is to believe the CFM specs of fan
> manufacturers and to then believe how much
> "air flow" there is through a case - with no
> consideration for the degree of turbulence.

That would be a mistake on two counts.

> "Air flow"
> is easy to believe in as a direct measure of heat
> transfer because it's so simple to measure.

Which is also incorrect.

> Turbulence, on the other hand, is hard to measure.

It's 'effects' wouldn't be.

> Just too begin with, what units do you use?
> But scientific researchers publish reports to show
> that turbulence has a definite effect on heat transfer
> between a moving fluid and an adjacent surface,
> and to ignore that by saying "It's irrelevant. It dies
> out soon after it's generated." is to deny why one
> swipe with your spoon will continue to stir your
> coffee

Hate to burst your bubble but coffee isn't air.

> or why walking through a smoke-filled
> room will leave the smoke swirling for a minute.

And a stagnant room isn't a PC case with constant airflow through it.

>
> *TimDaniels*
Anonymous
a b B Homebuilt system
June 16, 2004 12:58:03 PM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"David Maynard" wrote:
> There is no 'desire' to have it make a 'right angle turn';
> they end up doing it because a lot of people think it's
> friggin PRETTIER to not have the damn holes on the
> case front and there has to be a hole SOME where,
> so it ends up at the front bottom edge.

The fascia on my Dell Dimension is designed
to be exactly right for generating turbulence:

It has most of its right angle intake on the
front of the fascia - from two directions, at right
angles to each other - great for turbulence.
There is also an intake at the bottom of the
fascia at right angles to the inflows from the other
two openings - again great for turbulence.
Dell really got it right for turbulence

*TimDaniels*
Anonymous
a b B Homebuilt system
June 16, 2004 1:18:07 PM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"David Maynard" wrote:
> I gave you the NLX and ATX specs, which
> delineate maximum hole size for EMI shielding,
> and an entire article on using waveguide technology,
> for fan vents, to improve EMI shielding.


Care to post a link to those specs with a label
saying what they are this time? And a wire
grill would certainly keep hole size to ANY
maximum diameter desired.

As for
http://www.equipmentprotectionmagazine.com/eprints/UAF....,
you said:
"The air filter media itself plays a major role in keeping airflow
laminar."
"That's definitely an argument for not using a fan to blow into
the case after the air that has already gone through a grating,
isn't it?"

Would you expect a filter maker to say otherwise?

And AGAIN, the major manufacturers of PCs design their cases
so that they don't need fans at the intakes - homebuilders do that.


> > That you think holes
> > are to contain the EMI is *your* giant leap of faith.
>
> No, it comes from being in the business for 20 years.


<Gasp!> "In the business"! What business was that
and when were you in it?

*TimDaniels*>
Anonymous
a b B Homebuilt system
June 17, 2004 12:06:09 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

Timothy Daniels wrote:

> "David Maynard" wrote:
>
>>There is no 'desire' to have it make a 'right angle turn';
>>they end up doing it because a lot of people think it's
>>friggin PRETTIER to not have the damn holes on the
>>case front and there has to be a hole SOME where,
>>so it ends up at the front bottom edge.
>
>
> The fascia on my Dell Dimension is designed
> to be exactly right for generating turbulence:

You mean you fantasize that was 'the purpose' because that's what you WANT
'the purpose' to be.

>
> It has most of its right angle intake on the
> front of the fascia - from two directions, at right
> angles to each other - great for turbulence.
> There is also an intake at the bottom of the
> fascia at right angles to the inflows from the other
> two openings - again great for turbulence.
> Dell really got it right for turbulence

No, you have an active imagination that will interpret anything whatsoever
as 'right' and 'proof' of your fantasy.


>
> *TimDaniels*
Anonymous
a b B Homebuilt system
June 17, 2004 12:58:08 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"David Maynard"wrote:
> Timothy Daniels wrote:
> > Care to post a link to those specs with a label
> > saying what they are this time?
>
> I did the first time.


C'mon, Davey. Post the link.


> > Would you expect a filter maker to say otherwise?
>
> That's a silly question. If turbulence were such a great thing they'd have
> a sales point built and no need to go to all that effort to eliminate it.


And then they'd not have anything to sell.


> I have a DELL NLX case here that has a rear PSU and a <gasp>
> front case fan that sits in a giant gaping hole because, for one,
> there ain't no place to PUT a second fan in the rear. And the
> front fan was only installed when the 'high power' processor
> option was exercised because the airflow through the giant
> gaping hole in the front was sufficient for the smaller unit. In
> fact, the entire front of the chassis is a gaping hole with just
> enough of a panel to hold the power switch and a couple of LEDs.


That front fan provides the turbulence, then.


> The fact of the matter is that a PC case is anything BUT
> a nice smooth straight laminar flow path so that intentionally
> adding turbulence is the least of your worries. So much so
> 'the least' that reDUcing turbulence is the order of the day.


You continue to forget that the components that get
hit by fresh incoming air - the hard drives and the
lower PCI cards and part of the motherboard -
haven't hit anything, yet, and thus the turbulence you
believe they create hasn't built up, yet, either. The
way to get turbulence to the hard drives and those
other initial components in the air path is to add it
at the front.


> Electrical engineering and computer design.


Too bad aerodynamics and thermodynamics
weren't part of it.

*TimDaniels*
Anonymous
a b B Homebuilt system
June 17, 2004 4:28:29 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"David Maynard" fakes it:
> >>I gave you the NLX and ATX specs, which
> >>delineate maximum hole size for EMI shielding,
> >>and an entire article on using waveguide technology,
> >>for fan vents, to improve EMI shielding.
> >
> >
> >
> > Care to post a link to those specs with a label
> > saying what they are this time?
>
> I did the first time.


C'mon, Davey. Post the link. Let's see the ATX specs
which tell about EMI and the maximum size for vent holes.
C'mon, c'mon. I wanna learrrrrn. <hee, hee> :-)

*TimDaniels*
Anonymous
a b B Homebuilt system
June 17, 2004 6:19:02 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

Timothy Daniels wrote:

Stay in your self delusional la-la land.

<snip>
Anonymous
a b B Homebuilt system
June 17, 2004 8:51:56 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

Timothy Daniels wrote:

> "David Maynard" fakes it:
>
>>>>I gave you the NLX and ATX specs, which
>>>>delineate maximum hole size for EMI shielding,
>>>>and an entire article on using waveguide technology,
>>>>for fan vents, to improve EMI shielding.
>>>
>>>
>>>
>>> Care to post a link to those specs with a label
>>> saying what they are this time?
>>
>>I did the first time.
>
>
>
> C'mon, Davey. Post the link. Let's see the ATX specs
> which tell about EMI and the maximum size for vent holes.
> C'mon, c'mon. I wanna learrrrrn. <hee, hee> :-)
>
> *TimDaniels*

Suuuuure you do.

Okay, laughing boy, for the sake of variety, let's look at the microATX
thermal design suggestions from formfactor.org

http://www.formfactors.org/developer/specs/microatx_the...

"2.8.1 Chassis and Bezel Venting
Proper venting is a key element in any good thermal design. A balanced vent
configuration is a critical factor in this design. Implementing an
insufficient amount does not allow enough air into the system for adequate
cooling...

Key considerations:...

· Front chassis and bezel venting – The bezel vent area should be as large
as possible because it serves as the main air inlet for the system. Ensure
the plastic bezel vent pattern allows air to enter freely so it does not
overly restrict airflow into the system."

Note there is no mention to include 'right angle bends' in the 'fancy
3-dimensional molded tight tolerance plastic fascia' to accommodate 'Tims
turbulence theory'. No, it says 'allows air to enter FREELY." In fact, you
won't find one word about 'ensuring turbulence' anywhere, much less 'vent
hole turbulence'. Everything is eliminate resistance, eliminate resistance,
and eliminate resistance.


For EMI:

"(NOTE: To eliminate possible electromagnetic compliance issues, neither
the maximum vertical nor maximum horizontal dimensions of ventilation
apertures, I/O ports, and open areas along chassis seams less than 1/20th
of a wavelength of the highest harmonic frequency of interest.)"

Well, shazzam, an EMI caution.


Well, let's see what the microATX document specific for EMI says.

http://www.formfactors.org/developer%5Cspecs%5Cmatxemc....

"2.5.2 Apertures

Keep maximum linear dimensions of ventilation apertures, I/O ports, and
open areas along chassis seams less than 1/20th of a wavelength ( l ) of
the highest harmonic frequency ( f ) of concern (1/20th rule, see also
Figure 2). Absorption and shield thickness may contain low frequency
magnetic fields, but high frequency electric field radiation out of slots
becomes the next concern. Apertures (or slots) can be viewed as half-wave
dipole antennas and are thus able to radiate maximum energy at dimensions
of 1/2 a wavelength. In fact, slots longer than 1/100th of a wavelength can
cause considerable leakage. Therefore, it is necessary to keep slot lengths
as short as possible to minimize leakage. Currently, the FCC has
requirements up to 2 GHz, which, as derived below, correspond to a
recommended maximum aperture size (vertical or horizontal) of about .75
centimeters; for example:" (see PDF for the example equations.)

Converting to inches that means, for a nice el-cheapo stamped vent, round
holes under .295 inches.


And Intel discussion on EMI
http://www.intel.com/design/pentiumii/applnots/24333402...

Mostly processor, heatsink, and board layout but the chassis is mentioned
at the end.

"• Where possible, use round holes instead of slotted holes. Round holes
provide the greatest airflow volume for the least amount of EMI leakage."

Now you know why the holes are typically round.

In the interest of fair time we might as well see what AMD has to say about it.

http://www.amd.com/us-en/assets/content_type/white_pape...

Same comprehensive discussion centering on the electronics but then we also
have the chassis section.

Apertures in a Chassis: Apertures (vents, holes, seams, screens) in a
chassis can cause EMI leakage.

• Apertures radiate at wavelengths equal to or less than their length. The
length of an aperture is inversely proportional to the leaking resonant
frequency.
• Small holes and short seams prevent leakage of low frequencies.
• Circles have minimal width for a given area, so round vents are better
than slots (which are typically rectangular).
• Screens are the best vents because of their small hole size.
• Apertures should be shorter than one tenth of the wavelength to be
shielded. For instance:
• A 300-MHz frequency has a 1-meter wavelength, so boxes with harmonics
less than 300 MHz can have 10-centimeter apertures."

Well, whadda ya know, they say the same thing.


Inexpensive vent hole summary: Stamp enough under .295 inch diameter round
(so the FCC will stay off your butt) vent holes in the metal chassis where
you want air to enter. Put fascia on front so it looks pretty, making sure
there's plenty of room for air to get to the vent holes you stamped in the
metal chassis.
Anonymous
a b B Homebuilt system
June 17, 2004 10:42:24 PM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"David Maynard" switches to MicroATX:
>Timothy Daniels wrote:
>>>>I gave you the NLX and ATX specs, which
>>>>delineate maximum hole size for EMI shielding,
>>>>and an entire article on using waveguide technology,
>>>>for fan vents, to improve EMI shielding.
> [...]
>> C'mon, Davey. Post the link. Let's see the ATX specs
>> which tell about EMI and the maximum size for vent holes.
>> C'mon, c'mon. I wanna learrrrrn. <hee, hee> :-)
>
> Okay, laughing boy, for the sake of variety,
> let's look at the microATX thermal design
> suggestions from formfactor.org


Before we dance off to MicroATX,
we should note that the ATX specs
(http://www.formfactors.org/developer/specs/atx2_2.pdf)
make no mention of size of vent holes - versus EMI
or air flow or anything else.
Here is all the ATX specs say about cooling:


"Adequate venting should be provided in the system
to allow for unimpeded and well-directed airflow to
cool key components such as the processor. One
recommendation that is implicit in the ATX specification
is the placement of the power supply. The power supply
should be placed in close proximity to the processor if
the power supply is expected to cool the processor
properly (but be sure to observe the component height
keepouts over the PC board). Chassis venting should
be placed strategically to allow for proper cooling of
other components such as peripherals and add-in cards.
A system fan should be considered to allow for proper
cooling of all system components."

It says nothing about EMI from vents, nothing about size
of vents, nothing about quality of air flow except that it
should be "unimpeded" and "well-directed" to cool things
like the processor, and that the chassis venting should be
"placed strategically" to cool non-motherboard cards and
hard drives.

Now then, the MicroATX specs:

>http://www.formfactors.org/developer/specs/microatx_the...
>
>"2.8.1 Chassis and Bezel Venting
> Proper venting is a key element in any good thermal design.
> A balanced vent configuration is a critical factor in this design.
> Implementing an insufficient amount does not allow enough
> air into the system for adequate cooling...
>
> Key considerations:...
>
> Front chassis and bezel venting –
> The bezel vent area should be as large as possible because
> it serves as the main air inlet for the system. Ensure the plastic
> bezel vent pattern allows air to enter freely so it does not
> overly restrict airflow into the system."
>
> Note there is no mention to include 'right angle bends'
> in the 'fancy 3-dimensional molded tight tolerance plastic fascia'
> to accommodate 'Tims turbulence theory'. No, it says 'allows
> air to enter FREELY." In fact, you won't find one word about
> 'ensuring turbulence' anywhere, much less 'vent hole turbulence'.
> Everything is eliminate resistance, eliminate resistance, and
> eliminate resistance.


Read it again. It says "allows air to enter freely so it does not
OVERLY RESTRICT airflow into the system". It does not
define "overly", neither does it recommend against turbulence.

That MicroATX says nothing about turbulence of the air
flowing into the case only means that turbulence is hard
to define. How can anyone define how much swirl, what
diameter of vortices, their relative orientation, speed of
rotation, etc.? That is why it takes repeated a cut-'n-try
experimentation by the labs of the name brand vendors to
get it right and why the sellers of empty cases cannot compete.
To expect that such a low level of specification should be
contained in the MicroATX specs is to expect that all PCs
be built exactly the same. Obviously, there is no intention
of doing that. And there is no mention of "eliminate resistance"
of air flow at the entrance to the case. The free air flow
described is that which is WITHIN THE CASE, between
the components to be cooled. The greater efficiency in cooling
afforded by turbulent air is not all addressed by the MicroATX
spec because it is a technique used by the name brand vendors
to give better cooling with less cost and less intake noise.


> For EMI:
> "(NOTE: To eliminate possible electromagnetic compliance issues,
> neither the maximum vertical nor maximum horizontal dimensions
> of ventilation apertures, I/O ports, and open areas along chassis
> seams less than 1/20th of a wavelength of the highest harmonic
> frequency of interest.)"
>
> Well, shazzam, an EMI caution.


Well, shazzam, an EMI caution for MicroATX form factor.


> Well, let's see what the microATX document specific for EMI says.
> http://www.formfactors.org/developer%5Cspecs%5Cmatxemc....
>
> "2.5.2 Apertures
> Keep maximum linear dimensions of ventilation apertures,
> I/O ports, and open areas along chassis seams less than 1/20th
> of a wavelength ( l ) of the highest harmonic frequency ( f ) of
> concern (1/20th rule, see also Figure 2). Absorption and shield
> thickness may contain low frequency magnetic fields, but high
> frequency electric field radiation out of slots becomes the next
> concern. Apertures (or slots) can be viewed as half-wave
> dipole antennas and are thus able to radiate maximum energy
> at dimensions of 1/2 a wavelength. In fact, slots longer than
> 1/100th of a wavelength can cause considerable leakage.
> Therefore, it is necessary to keep slot lengths as short as
> possible to minimize leakage. Currently, the FCC has
> requirements up to 2 GHz, which, as derived below, correspond
> to a recommended maximum aperture size (vertical or horizontal)
> of about .75 centimeters; for example:" (see PDF for the example
> equations.)
>
> Converting to inches that means, for a nice el-cheapo stamped
> vent, round holes under .295 inches.



Hmmm... you missed section 2.5.7 which says:

"A large number of small holes give better shielding than
a single large hole of the same area. Either large holes
or small holes placed too close together can become
significant slot antennas. Space small holes apart by
a distance equal to the diameter of the hole ( l / 20).
Reduce emissions from large holes by placing screens over
large holes or forming a 'waveguide below cutoff.'"

In other words, a WIRE GRILL over one big hole would
give the same protection against EMI.


> And Intel discussion on EMI
>http://www.intel.com/design/pentiumii/applnots/24333402...
>
> Mostly processor, heatsink, and board layout but the chassis
> is mentioned at the end.
>
> "• Where possible, use round holes instead of slotted holes.
> Round holes provide the greatest airflow volume for the least
> amount of EMI leakage."
>
> Now you know why the holes are typically round.
>
> In the interest of fair time we might as well see what AMD
> has to say about it.
>
>http://www.amd.com/us-en/assets/content_type/white_pape...
df
>
> Same comprehensive discussion centering on the electronics
> but then we also have the chassis section.
>
> Apertures in a Chassis: Apertures (vents, holes, seams, screens)
> in a chassis can cause EMI leakage.
>
> • Apertures radiate at wavelengths equal to or less than their length.
> The length of an aperture is inversely proportional to the leaking
> resonant frequency.
> • Small holes and short seams prevent leakage of low frequencies.
> • Circles have minimal width for a given area, so round vents are
> better than slots (which are typically rectangular).
> • Screens are the best vents because of their small hole size.
> • Apertures should be shorter than one tenth of the wavelength
> to be shielded. For instance:
> • A 300-MHz frequency has a 1-meter wavelength, so boxes
> with harmonics less than 300 MHz can have 10-centimeter
> apertures."
>
> Well, whadda ya know, they say the same thing.



Yup:
"Screens are the best vents because of their small hole size."
It confirms that a simple WIRE GRILL would have the same
effect as a lot of small holes.


> Inexpensive vent hole summary: Stamp enough under .295 inch
> diameter round (so the FCC will stay off your butt) vent holes
> in the metal chassis where you want air to enter. Put fascia on
> front so it looks pretty, making sure there's plenty of room for
> air to get to the vent holes you stamped in the metal chassis.


It says nothing about how air is to get into the case, but only
that it have free flow once inside the case in order to get to
the components to be cooled. That is one of your blind spots -
you confuse free air flow inside the case with freedom to enter
the case.

And besides being pretty, the fascias designed by the big vendors
direct the air NOT smoothly and NOT directly into the holes
with their molded plastic fascias, but at various 90 degree angles
to maximize the turbulence.

And ask yourself why the name brand vendors didn't take
one of those cheap wire grills that they put over air exhaust
fans and put it over one big hole in the front. That one big
hole would allow almost NO AIR RESTRICTION, and the
grill would block the EMI much more effectively. Why did
they do that? Because the entering air would have little
turbulence. Instead, they went with a bunch of little holes
having a much greater edge-to-area ratio - which increases
turbulence.

*TimDaniels*
Anonymous
a b B Homebuilt system
June 18, 2004 6:44:21 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

Timothy Daniels wrote:

<snip>

>
> And ask yourself why the name brand vendors didn't take
> one of those cheap wire grills that they put over air exhaust
> fans and put it over one big hole in the front. That one big
> hole would allow almost NO AIR RESTRICTION, and the
> grill would block the EMI much more effectively. Why did
> they do that? Because the entering air would have little
> turbulence. Instead, they went with a bunch of little holes
> having a much greater edge-to-area ratio - which increases
> turbulence.

No, because the punched holes are FREE.

Inexpensive vent hole summary: Stamp enough under .295 inch
diameter round (so the FCC will stay off your butt) vent holes
in the metal chassis where you want air to enter. Put fascia on
front so it looks pretty, making sure there's plenty of room for
air to get to the vent holes you stamped in the metal chassis.

And that's the end of it.
Anonymous
a b B Homebuilt system
June 18, 2004 2:28:53 PM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"David Maynard" wrote:
> No, because the punched holes are FREE.


Which make a lot of turbulence and which restrict
the air flow. If case designers were concerned
with restriction of intake air so as to want to
minimize it, they wouldn't use holes in a flat metal
chassis wall for ventilation. They's use one big
hole with a screen or grill over it. Instead they
designed a lot of holes (maximizing the amount
of sharp edges in their expensive tooling, by the
way) which maximizes the turbulence. Then, to
maximize that turbulence, they direct air at the
holes from multiple right angles with a plastic
fascia to further turbulate the air. Why did the
designers agree to such a high price in intake
air restriction if it weren't to produce turbulence,
which a plethora of research shows to increase
heat transfer?

*TimDaniels*
Anonymous
a b B Homebuilt system
June 18, 2004 11:52:57 PM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

Timothy Daniels wrote:

> "David Maynard" wrote:
>
>>No, because the punched holes are FREE.
>
>
>
> Which make a lot of turbulence and which restrict
> the air flow. If case designers were concerned
> with restriction of intake air so as to want to
> minimize it, they wouldn't use holes in a flat metal
> chassis wall for ventilation. They's use one big
> hole with a screen or grill over it. Instead they
> designed a lot of holes (maximizing the amount
> of sharp edges in their expensive tooling, by the
> way) which maximizes the turbulence. Then, to
> maximize that turbulence, they direct air at the
> holes from multiple right angles with a plastic
> fascia to further turbulate the air. Why did the
> designers agree to such a high price in intake
> air restriction if it weren't to produce turbulence,
> which a plethora of research shows to increase
> heat transfer?

I've explained it already, more than once, and you asking the same already
answered questions is a waste of time. Either learn what you've already
been told or live in ignorance. I care not which.
Anonymous
a b B Homebuilt system
June 22, 2004 2:20:23 PM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

"Timothy Daniels" <TDaniels@NoSpamDot.com> wrote in message
news:2M2dneE9UIbMu07dRVn-vw@comcast.com...
> "David Maynard" wrote:
> > No, because the punched holes are FREE.
>
>
> Which make a lot of turbulence and which restrict
> the air flow. If case designers were concerned
> with restriction of intake air so as to want to
> minimize it, they wouldn't use holes in a flat metal
> chassis wall for ventilation. They's use one big
> hole with a screen or grill over it. Instead they
> designed a lot of holes (maximizing the amount
> of sharp edges in their expensive tooling, by the
> way) which maximizes the turbulence. Then, to
> maximize that turbulence, they direct air at the
> holes from multiple right angles with a plastic
> fascia to further turbulate the air. Why did the
> designers agree to such a high price in intake
> air restriction if it weren't to produce turbulence,
> which a plethora of research shows to increase
> heat transfer?
>
> *TimDaniels*

Could it ever be possible that the present system just happens to work
quite well?

Ed

btw, this entire thread (by Mr. Daniels) is kind of pointless as far as
practical cooling is concerned. You are talking in 1-2 degrees, if any at
all. There are many much more important things for me to worry about when I
build a system. I still say that the most important thing to me, as far as
cooling is concerned, is to get as much hot air out and as much cool air in
that I can without a ton of noise. I am quite sure that between David and I,
we have built more systems than you have been alive in years. GOOD AIRFLOW.
Get it?
Anonymous
a b B Homebuilt system
June 29, 2004 11:08:38 AM

Archived from groups: alt.comp.hardware.homebuilt (More info?)

OK, i can kinda see benifets to both sides of this story. What about
this?
I have 2 fans exhausting and 2 in the front pulling into my system.
One of which is pulling across my harddrives. I'm sure this creates a
fair amount of turbulence but could this setup be too much? I guess
what i'm trying to say is do i have so much velocity now that i'm not
getting the desired amount of turbulence? My system runs cool as a
cucumber, but it's hardly mean enough to create any real heat
problems. Just a thought. I've often wondered about this. My case is
designed this way so i'm just using what i have. And if your
wondering, the noise level is surprisingly minimal. Sure, you can
hear it but it's not bothersome.

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