Fan Flow Direction

[Guest]

Archived from groups: alt.sys.pc-clone.gateway2000 (More info?)

I replaced my computer's 90-watt Newton power supply with a 180-watt Fortron
power supply today. I have not added any other new components, so the total
power consumed should not have changed. The new power supply unit (PSU) fits
perfectly in every way except one: The air flow direction is reversed. The old
fan's intake was on the back of the computer case. The old fan's exhaust was
into the computer, across the heat sink and CPU, and out the back of the case.
The old way arguably caused the case to be under a slight pressure.

The new fan arguably puts the case under a slight vacuum.

The heat sink prongs are hot but not so hot I can't safely (no burns) leave a
finger on it.

Should I just observe for awhile, playing it by ear?

Or should I figure out a way to reverse the fan flow direction in the new power
supply?

All experience is welcome. I googled and am not finding anything definitive.

Aside: After a lot of research on physical fit and electrical fit, brand names,
and cost, I bought the new power supply from newegg.com. With shipping,
altogether it cost $26. Ordered Tuesday night late, arrived Friday afternoon.

 

[Rocket]

Archived from groups: alt.sys.pc-clone.gateway2000 (More info?)

There would be no value in having even the slightest pressure inside of a
case.

Physics tells us two things about pressure and temperature:
1) Pressure directly affects temperature: higher pressure = higher temps,
lower pressure = lower temps.
It's the primary mechanics of AC and Heat Pumps.
2) There is no "cold", only the absence of heat; therefore, the key to
cooling is the removal of heat.
The more heat that can be removed must result in lower temps = happy PC.

All that aside:
The number of fans, airflow amounts and CFM values are all meaningless
unless there is a place to flow through (i.e. intake --> exhaust).
Normally case intake is through front case bezel (sometimes a fan) and
sometimes additional side intake fan, snorkel, or direct ducted CPU. Exhaust
is usually through PSU and sometimes additional rear case fan(s) and/or top
blowhole fan(s).

Many people add more fans thinking to provide more airflow but in the end if
?-P[exhaust] doesn't equal or slightly exceed ?+P[intake], then ?-T
[cooling] won't be effective and the only result will be a fan-battle stress
test.
--
Rocket


"Caroline" <caroline10027remove@earthlink.net> wrote in message
news:W7cpc.723$H_3.570@newsread1.news.pas.earthlink.net...
> I replaced my computer's 90-watt Newton power supply with a 180-watt
Fortron
> power supply today. I have not added any other new components, so the
total
> power consumed should not have changed. The new power supply unit (PSU)
fits
> perfectly in every way except one: The air flow direction is reversed. The
old
> fan's intake was on the back of the computer case. The old fan's exhaust
was
> into the computer, across the heat sink and CPU, and out the back of the
case.
> The old way arguably caused the case to be under a slight pressure.
>
> The new fan arguably puts the case under a slight vacuum.
>
> The heat sink prongs are hot but not so hot I can't safely (no burns)
leave a
> finger on it.
>
> Should I just observe for awhile, playing it by ear?
>
> Or should I figure out a way to reverse the fan flow direction in the new
power
> supply?
>
> All experience is welcome. I googled and am not finding anything
definitive.
>
> Aside: After a lot of research on physical fit and electrical fit, brand
names,
> and cost, I bought the new power supply from newegg.com. With shipping,
> altogether it cost $26. Ordered Tuesday night late, arrived Friday
afternoon.
>
>

 

[Rocket]

Archived from groups: alt.sys.pc-clone.gateway2000 (More info?)

Sorry,
"?" in previous post was intended to be Greek (Delta)[Differential] term but
I hope my point was clear.
--
Rocket

 

[Guest]

Archived from groups: alt.sys.pc-clone.gateway2000 (More info?)

"Rocket" <rocket@spamcop.net> wrote
> There would be no value in having even the slightest pressure inside of a
> case.
>
> Physics tells us two things about pressure and temperature:
> 1) Pressure directly affects temperature: higher pressure = higher temps,
> lower pressure = lower temps.

You're assuming the specific volume is fixed. Don't.

Not that this has any particular bearing on the problem at hand...

> It's the primary mechanics of AC and Heat Pumps.
> 2) There is no "cold", only the absence of heat; therefore, the key to
> cooling is the removal of heat.

There is neither absolute heat nor absolute cold. Rather, there is heat transfer
caused by a temperature difference.

> The more heat that can be removed must result in lower temps = happy PC.

The more air flow through the casing, the lower the steady state air temperature
in the casing, the greater the heat transfer from CPU (or whatever) to moving
air, the lower the temperature of the CPU.

> All that aside:
> The number of fans, airflow amounts and CFM values are all meaningless
> unless there is a place to flow through (i.e. intake --> exhaust).
> Normally case intake is through front case bezel (sometimes a fan) and
> sometimes additional side intake fan, snorkel, or direct ducted CPU. Exhaust
> is usually through PSU and sometimes additional rear case fan(s) and/or top
> blowhole fan(s).
>
> Many people add more fans thinking to provide more airflow but in the end if
> ?-P[exhaust] doesn't equal or slightly exceed ?+P[intake], then ?-T
> [cooling] won't be effective and the only result will be a fan-battle stress
> test.

I cannot decipher what you mean by ?-P[exhaust], etc.