Crackheads need for crackpot solutions to frosty problem.

Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

A friend of mine put his washer and dryer in the basement
instead of in the ground-floor laundry room of the house
he moved into last winter. The laundry room was then
turned into his office.

Over the summer I used the existing dryer exhaust vent
to duct the hot exhaust air from his Opteron dualie directly
to the great outdoors. That changed the office from being
uncomfortably warm on hot days to being just another room.

We decided to try something different for the winter:
use the duct to draw cold air in from outside, cool the
computer, and then exhaust the warmed up air to the room.

That usually works great: on most days even under load
the cpu fans automatically turn themselves to their slowest
speed and the case fan and PSU fan can be manually turned
to their lowest speeds and everything run nice and cool.
The silence is deafening.

However, today it hit -33'C and now the air coming out the
back of the PSU is -5'C, which cools the room off pretty
darned fast. We tried ducting the cold exhaust air back
outside - which solved the room temperature problem nicely.

(The turning point seems to be about -18'C: cold air into
the computer, room temperature air out.)

However, when we do that a new problem crops up: frost builds
up on the outside of the case and also on things inside the
case that don't produce enough heat. We can't for the life
of us figure out why ducting the cold exhaust back outside
is causing this. When I stand on a ladder outside the house,
airflow from the exhaust duct is good and is noticably much
warmer than the ambient outside temperature.

One more datum: If we disconnect the five foot flexible
insulated exhaust duct from the hole in the wall and let
the exhaust blow through the ducting and into the room,
the frost problem goes away. Hook that duct back up to
the hole in the wall and the frost comes back.

Also: both the intake duct and the exhaust duct are about
4 feet above the floor in the room and horizontally about
2 feet apart. Outside, that places them about 10 feet above
the ground and 5 feet below the soffits. It is a breezy day,
but that side of the house is out of the wind.
25 answers Last reply
More about crackheads crackpot solutions frosty problem
  1. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    "Rob Stow" <rob.stow.nospam@shaw.ca> wrote in message
    news:XoCCd.705612$%k.370482@pd7tw2no...
    >


    At -33C, the outside air is very dry and when you vent it into the room you
    are displacing warmer and moister air, particularly in the immediate
    vicinity of the computer.

    Once you vent the air from the computer outside again you are romoving this
    drying effect in the vicinity of the computer. You may think this will only
    affect the outside of the case, but there are lots of litle holes, exetra,
    in your computer and air from the room will be drawn inside somewhere
    (ventri effect).

    Nice idea, but you will have to isolate the computer from the room, if you
    want it to work with out frost.
  2. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    OK you crazy guy, I'll bite:

    Rob Stow <rob.stow.nospam@shaw.ca> wrote:
    > However, today it hit -33'C and now the air coming out the
    > back of the PSU is -5'C, which cools the room off pretty
    > darned fast. We tried ducting the cold exhaust air back
    > outside - which solved the room temperature problem nicely.

    But you will frost the box from warm (semi-humid) house air.
    When you exhaust to the room, it fills with dry outside air.

    > (The turning point seems to be about -18'C: cold air into
    > the computer, room temperature air out.)

    OK, so put a side damper on the cold air to the PSU. Bleed some
    warm room air in. Do not mix in humid air, or you could get
    moisture in the PSU. This shouldn't be a problem if the case
    fans are strong enough to put the room under positive pressure.
    But watch out for static electricity in that bone-dry room!

    -- Robert
  3. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    Steve wrote:
    > "Rob Stow" <rob.stow.nospam@shaw.ca> wrote in message
    > news:XoCCd.705612$%k.370482@pd7tw2no...
    >
    >
    >
    > At -33C, the outside air is very dry and when you vent it into the room you
    > are displacing warmer and moister air, particularly in the immediate
    > vicinity of the computer.
    >
    > Once you vent the air from the computer outside again you are romoving this
    > drying effect in the vicinity of the computer. You may think this will only
    > affect the outside of the case, but there are lots of litle holes, exetra,
    > in your computer and air from the room will be drawn inside somewhere
    > (ventri effect).
    >
    > Nice idea, but you will have to isolate the computer from the room, if you
    > want it to work with out frost.
    >
    >

    Thanks. That makes sense at a first reading. I'll
    have supper, a couple of beers, sleep on it and hopefully
    it will still make sense ;-)

    Sounds like it should be easy to verify this by shrouding
    the computer in plastic and using tape to seal where the
    ducts go into and out of the plastic. Not as a permanent
    solution of course - just an experiment.

    It's up to -25'C now but it is supposed to cool off again
    overnight. Here's the forecast for Hell, if anyone is
    interested:
    http://www.theweathernetwork.com/weather/cities/can/pages/CASK0210.htm
  4. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    On Tue, 04 Jan 2005 19:47:03 GMT, Rob Stow <rob.stow.nospam@shaw.ca> wrote:
    [snipped]

    No cures, I just want to compliment you on your subject line.

    It's....perfect ;-)
  5. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    On Tue, 04 Jan 2005 22:43:54 +0000, daytripper wrote:

    > On Tue, 04 Jan 2005 19:47:03 GMT, Rob Stow <rob.stow.nospam@shaw.ca> wrote:
    > [snipped]
    >
    > No cures, I just want to compliment you on your subject line.
    >
    > It's....perfect ;-)

    'tripper, you are such a silver-tounged devil!

    --
    Keith
  6. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    would it not be a lot safer to build a simple heat exchanger then no
    particles from outside and condensation can be kept away from the
    electronic components
  7. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    ewan wrote:
    > would it not be a lot safer to build a simple heat exchanger then no
    > particles from outside and condensation can be kept away from the
    > electronic components

    Probably, but what has been done so far was accomplished
    with nothing more that a little duct tape and $10 worth
    of insulated 4" flexible ducting.

    Somewhat along the heat exchanger idea I have been consider
    getting a water cooling kit for myself and putting a fanless
    radiator outside. Obviously I would have to use something
    like ethylene-glycol as the coolant.

    I've been trying to persuade my friend to try the water
    cooling idea first. He owns a house that already has
    holes in the wall, whereas I rent.
  8. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    Thus spake Rob Stow:
    <Snipped>
    > Also: both the intake duct and the exhaust duct are about
    > 4 feet above the floor in the room and horizontally about
    > 2 feet apart. Outside, that places them about 10 feet above
    > the ground and 5 feet below the soffits. It is a breezy day,
    > but that side of the house is out of the wind.

    -33C, heavens, that's cold. The temp dropped to -18C once about 20yrs ago
    where I live 40m west of London! The lowest recorded temp for the UK appears
    to have been -27C in Scotland & about -23C in England. Where your quoted
    site says "Feels like", I presume that's wind chill.
  9. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    Paul Busby wrote:
    > Thus spake Rob Stow:
    > <Snipped>
    >
    >>Also: both the intake duct and the exhaust duct are about
    >>4 feet above the floor in the room and horizontally about
    >>2 feet apart. Outside, that places them about 10 feet above
    >>the ground and 5 feet below the soffits. It is a breezy day,
    >>but that side of the house is out of the wind.
    >
    >
    > -33C, heavens, that's cold. The temp dropped to -18C once about 20yrs ago
    > where I live 40m west of London! The lowest recorded temp for the UK appears
    > to have been -27C in Scotland & about -23C in England.

    The average temp here for January is about -16'C, so
    obviously we get a few nice days to balance out the
    cold ones.


    > Where your quoted site says "Feels like", I presume that's wind chill.

    Yeah, its wind chill. Everyone had been using
    "wind chill" for a million years and then some bright
    boy decided that it was too technical a term for a
    public web site. Go figure.
  10. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    Thus spake Rob Stow:
    >> <Snipped>
    > The average temp here for January is about -16'C, so
    > obviously we get a few nice days to balance out the
    > cold ones.
    >
    In some respects I envy you Rob: the only reliable way to tell the seasons
    in Blighty is by the amount of leaves on trees. Then again, I haven't lived
    in a truly cold climate, so I may have an over-romantic view.
  11. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    Paul Busby wrote:
    > Thus spake Rob Stow:
    >
    >>><Snipped>
    >>
    >>The average temp here for January is about -16'C, so
    >>obviously we get a few nice days to balance out the
    >>cold ones.
    >>
    >
    > In some respects I envy you Rob: the only reliable way to tell the seasons
    > in Blighty is by the amount of leaves on trees. Then again, I haven't lived
    > in a truly cold climate, so I may have an over-romantic view.
    >
    >

    We get the best of both worlds here: cold, snowy winters;
    warm rainy springs; hot dry summers; pleasant autumns.

    Of course that doesn't stop me from grousing when it
    hits -40'C in the winter or +40'C in the summer. ;-)
    Even -30'C annoying if it lasts more than a few days.
  12. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    Bitstring <RRWCd.716970$%k.38805@pd7tw2no>, from the wonderful person
    Rob Stow <rob.stow.nospam@shaw.ca> said
    <snip>
    >We get the best of both worlds here: cold, snowy winters;
    >warm rainy springs; hot dry summers; pleasant autumns.

    Yes, we get all that too .. sometimes in the same week. 8>.

    --
    GSV Three Minds in a Can
    Outgoing Msgs are Turing Tested,and indistinguishable from human typing.
  13. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    On Tue, 04 Jan 2005 19:47:03 GMT, Rob Stow <rob.stow.nospam@shaw.ca> wrote:

    >A friend of mine put his washer and dryer in the basement
    >instead of in the ground-floor laundry room of the house
    >he moved into last winter. The laundry room was then
    >turned into his office.

    Hmmm, I hope he has a washer which "supports" the stand-pipe height - many
    are limited to ~6 feet vertical "climb".

    >Over the summer I used the existing dryer exhaust vent
    >to duct the hot exhaust air from his Opteron dualie directly
    >to the great outdoors. That changed the office from being
    >uncomfortably warm on hot days to being just another room.
    >
    >We decided to try something different for the winter:
    >use the duct to draw cold air in from outside, cool the
    >computer, and then exhaust the warmed up air to the room.
    >
    >That usually works great: on most days even under load
    >the cpu fans automatically turn themselves to their slowest
    >speed and the case fan and PSU fan can be manually turned
    >to their lowest speeds and everything run nice and cool.
    >The silence is deafening.
    >
    >However, today it hit -33'C and now the air coming out the
    >back of the PSU is -5'C, which cools the room off pretty
    >darned fast. We tried ducting the cold exhaust air back
    >outside - which solved the room temperature problem nicely.

    If that's basically your case temp it's far too low for many of the
    components in the system, which can have a min operating temp of ~5C - hell
    some have a min specified storage temp of -5->-10C. On top of that the
    extremes of temp between Summer and Winter and On/Off are going to cause
    temp ramps which can cause damage, not to mention operating temp gradients
    on individual components and excessive fretting of contacts. Check the HDD
    first for min operating temp.

    >(The turning point seems to be about -18'C: cold air into
    >the computer, room temperature air out.)
    >
    >However, when we do that a new problem crops up: frost builds
    >up on the outside of the case and also on things inside the
    >case that don't produce enough heat. We can't for the life
    >of us figure out why ducting the cold exhaust back outside
    >is causing this. When I stand on a ladder outside the house,
    >airflow from the exhaust duct is good and is noticably much
    >warmer than the ambient outside temperature.

    Do you have a vent hood/flap on the exhaust vent, as one has with a dryer
    exhaust? I don't see how you can seal the case well enough to prevent the
    leakage in of some ambient room air.

    >One more datum: If we disconnect the five foot flexible
    >insulated exhaust duct from the hole in the wall and let
    >the exhaust blow through the ducting and into the room,
    >the frost problem goes away. Hook that duct back up to
    >the hole in the wall and the frost comes back.
    >
    >Also: both the intake duct and the exhaust duct are about
    >4 feet above the floor in the room and horizontally about
    >2 feet apart. Outside, that places them about 10 feet above
    >the ground and 5 feet below the soffits. It is a breezy day,
    >but that side of the house is out of the wind.

    I'd suggest you just disconnect the external air duct in Winter and use the
    computer as a background heater... unless maybe it's an overclocking
    project.:-)

    Rgds, George Macdonald
  14. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    Thus spake Rob Stow:
    > Paul Busby wrote:
    >> Thus spake Rob Stow:
    >>
    >>>> <Snipped>
    >>>
    >>> The average temp here for January is about -16'C, so
    >>> obviously we get a few nice days to balance out the
    >>> cold ones.
    >>>
    >>
    >> In some respects I envy you Rob: the only reliable way to tell the
    >> seasons in Blighty is by the amount of leaves on trees. Then again,
    >> I haven't lived in a truly cold climate, so I may have an
    >> over-romantic view.
    >
    > We get the best of both worlds here: cold, snowy winters;
    > warm rainy springs; hot dry summers; pleasant autumns.
    >
    > Of course that doesn't stop me from grousing when it
    > hits -40'C in the winter or +40'C in the summer. ;-)
    > Even -30'C annoying if it lasts more than a few days.

    Damn your wonderful weather Sir! I just phoned my brother on the subject who
    runs a modest weather station. He suggested the phrase "Feels like" isn't
    just wind chill but also factors in humidity to more closely resemble the
    subjective feeling of coldness. Seems fair enough.

    I used to take daily temp & humidity readings for a test equipment cal house
    which involved using a swinging wet bulb thermometer, we never used the
    bench hydrometer/thermometer which used a sprung-loaded multistranded horse
    hair mech attached to a pen against a cylinder of paper! One could improvise
    with a violin & clock of course (should they be to hand)!
  15. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    George Macdonald wrote:
    > On Tue, 04 Jan 2005 19:47:03 GMT, Rob Stow <rob.stow.nospam@shaw.ca> wrote:
    >
    >
    >>A friend of mine put his washer and dryer in the basement
    >>instead of in the ground-floor laundry room of the house
    >>he moved into last winter. The laundry room was then
    >>turned into his office.
    >
    >
    > Hmmm, I hope he has a washer which "supports" the stand-pipe height - many
    > are limited to ~6 feet vertical "climb".

    The stand-pipe is only about three feet tall.

    >
    >
    >>Over the summer I used the existing dryer exhaust vent
    >>to duct the hot exhaust air from his Opteron dualie directly
    >>to the great outdoors. That changed the office from being
    >>uncomfortably warm on hot days to being just another room.
    >>
    >>We decided to try something different for the winter:
    >>use the duct to draw cold air in from outside, cool the
    >>computer, and then exhaust the warmed up air to the room.
    >>
    >>That usually works great: on most days even under load
    >>the cpu fans automatically turn themselves to their slowest
    >>speed and the case fan and PSU fan can be manually turned
    >>to their lowest speeds and everything run nice and cool.
    >>The silence is deafening.
    >>
    >>However, today it hit -33'C and now the air coming out the
    >>back of the PSU is -5'C, which cools the room off pretty
    >>darned fast. We tried ducting the cold exhaust air back
    >>outside - which solved the room temperature problem nicely.
    >
    >
    > If that's basically your case temp it's far too low for many of the
    > components in the system, which can have a min operating temp of ~5C - hell
    > some have a min specified storage temp of -5->-10C. On top of that the
    > extremes of temp between Summer and Winter and On/Off are going to cause
    > temp ramps which can cause damage, not to mention operating temp gradients
    > on individual components and excessive fretting of contacts. Check the HDD
    > first for min operating temp.
    >

    The hard drives do quite well. The cold air intake is
    never opened up until after the system has been powered
    up, so the drives never really have a chance to cool off.

    Nevertheless, I will consider doing something like setting
    up a lowest-priority task to continuously copy a small file
    back and forth between the drives to make sure they never
    go idle.

    The DVD drive, however, has been a concern.

    >
    >>(The turning point seems to be about -18'C: cold air into
    >>the computer, room temperature air out.)
    >>
    >>However, when we do that a new problem crops up: frost builds
    >>up on the outside of the case and also on things inside the
    >>case that don't produce enough heat. We can't for the life
    >>of us figure out why ducting the cold exhaust back outside
    >>is causing this. When I stand on a ladder outside the house,
    >>airflow from the exhaust duct is good and is noticably much
    >>warmer than the ambient outside temperature.
    >
    >
    > Do you have a vent hood/flap on the exhaust vent, as one has with a dryer
    > exhaust? I don't see how you can seal the case well enough to prevent the
    > leakage in of some ambient room air.
    >

    There is a hood but no flap. Just a quarter inch
    mesh to keep out birds ;-) There is a lever on
    each vent close them when the computer is not in
    use.

    >
    >>One more datum: If we disconnect the five foot flexible
    >>insulated exhaust duct from the hole in the wall and let
    >>the exhaust blow through the ducting and into the room,
    >>the frost problem goes away. Hook that duct back up to
    >>the hole in the wall and the frost comes back.
    >>
    >>Also: both the intake duct and the exhaust duct are about
    >>4 feet above the floor in the room and horizontally about
    >>2 feet apart. Outside, that places them about 10 feet above
    >>the ground and 5 feet below the soffits. It is a breezy day,
    >>but that side of the house is out of the wind.
    >
    >
    > I'd suggest you just disconnect the external air duct in Winter and use the
    > computer as a background heater... unless maybe it's an overclocking
    > project.:-)

    Its a silencing project. The motherboard (Tyan S2885) doesn't
    provide much in the way of overclocking capabilities ;-)

    Cooling the system with cold air allows both CPU fans, the
    PSU fan, and the single case fan to all run at their slowest
    speeds. And - so far - the Radeon 9800 Pro has been quite
    happy with passive cooling.

    When cooling with air from inside the house, not only do all
    of the fans need to spin faster - and much louder - but a
    second case fan is also needed.
  16. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    We have kludged up something that so far seems to work,
    but a real test will have to wait until temperatures
    fall again - it is only -21'C tonight.

    We have connected the case fan to a thermostat, with
    the exhaust air from the PSU blowing over the thermostat.
    The PSU exhaust is no longer vented back outside. The
    120 mm case fan has also been replaced with an 80 mm fan
    with no increase in RPMs.

    As many air gaps as possible were sealed with tape on the
    /inside/ of the case. Around front drive bay covers, for
    example. The side panels now feature weatherstripping. :-)
    This should dramatically reduce the amount of warm, moist
    indoor air that leaks into the case.

    The case fan now only kicks in when the PSU exhaust
    convinces the thermostat that the temperature has risen
    to 15'C. In case it was not clear, the case fan is used
    to draw the cold air in from outside and blow it into
    the case. When the case fan is not running, the PSU fan
    does all of the work.

    At -21'C outdoor temp, the case fan spins about 80% of
    the time.
  17. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    On Thu, 06 Jan 2005 07:32:50 GMT, Rob Stow <rob.stow.nospam@shaw.ca>
    wrote:

    >We have kludged up something that so far seems to work,
    >but a real test will have to wait until temperatures
    >fall again - it is only -21'C tonight.
    >
    >We have connected the case fan to a thermostat, with
    >the exhaust air from the PSU blowing over the thermostat.
    >The PSU exhaust is no longer vented back outside. The
    >120 mm case fan has also been replaced with an 80 mm fan
    >with no increase in RPMs.
    >
    >As many air gaps as possible were sealed with tape on the
    >/inside/ of the case. Around front drive bay covers, for
    >example. The side panels now feature weatherstripping. :-)
    >This should dramatically reduce the amount of warm, moist
    >indoor air that leaks into the case.
    >
    >The case fan now only kicks in when the PSU exhaust
    >convinces the thermostat that the temperature has risen
    >to 15'C. In case it was not clear, the case fan is used
    >to draw the cold air in from outside and blow it into
    >the case. When the case fan is not running, the PSU fan
    >does all of the work.
    >
    >At -21'C outdoor temp, the case fan spins about 80% of
    >the time.

    I like the idea, which I had a hole in my PC room wall! ;p

    I'd probably add some desiccant packs (big ones) to the bottom and top
    of the inside of the case to help keep moisture at a minimum, not sure
    how much they'd really last or help though with constant moving air.

    What sort of system do you have, you doing some massive over clocking or
    just going for max cool and quite?

    Cheers,
    Ed
    --
    O'Hare Airport-Light Snow-25F
  18. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    Rob Stow <rob.stow.nospam@shaw.ca> wrote:
    > The PSU exhaust is no longer vented back outside.
    > The 120 mm case fan has also been replaced with an
    > 80 mm fan with no increase in RPMs.

    This is a _huge_ change. That case fan capacity has been
    reduced by ~56%. From always positive, the case pressure
    may now go negative so you'll need ...

    > As many air gaps as possible were sealed with tape on
    > the /inside/ of the case. Around front drive bay covers,

    It's still very hard to seal tight.

    > The case fan now only kicks in when the PSU exhaust convinces
    > the thermostat that the temperature has risen to 15'C.
    > In case it was not clear, the case fan is used to draw the
    > cold air in from outside and blow it into the case. When the
    > case fan is not running, the PSU fan does all of the work.

    And at these times, the case is at minimum pressure.

    > At -21'C outdoor temp, the case fan spins about 80% of
    > the time.

    Interesting. That's one hot box, or airflow is somehow
    restricted. IIRC, an 80 mm fan moves about 7cfm (depending
    on speed & restrictions). 7cfm @ 15'C is about 4.3 g/s.
    Warming air 36C' requires 36 J/g. So that box was putting
    out 155W. That's quite a bit for a machine at idle.

    -- Robert
  19. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    Robert Redelmeier wrote:
    > Rob Stow <rob.stow.nospam@shaw.ca> wrote:
    >
    >>The PSU exhaust is no longer vented back outside.
    >>The 120 mm case fan has also been replaced with an
    >>80 mm fan with no increase in RPMs.
    >
    >
    > This is a _huge_ change. That case fan capacity has been
    > reduced by ~56%. From always positive, the case pressure
    > may now go negative so you'll need ...
    >

    The 120 mm fan went back in.

    It got all the way up to -12'C and when the air is that warm
    the 80 mm fan just can't push enough air into the case unless
    we run it at its medium speed. At that speed it is noticeably
    noisier than the slower 120 mm fan while still moving less air
    We figure it is about 7 cfm for 80 mm at medium speed vs
    10 cfm for 120 mm at slow speed. And the whole point of this
    scheme is noise reduction.

    >
    >>As many air gaps as possible were sealed with tape on
    >>the /inside/ of the case. Around front drive bay covers,
    >
    >
    > It's still very hard to seal tight.
    >

    Even so, we got it tight enough that even with the 80 mm
    fan we had positive pressure in the case. But, of course,
    negative pressure when the fan wasn't spinning.


    >
    >>The case fan now only kicks in when the PSU exhaust convinces
    >>the thermostat that the temperature has risen to 15'C.
    >>In case it was not clear, the case fan is used to draw the
    >>cold air in from outside and blow it into the case. When the
    >>case fan is not running, the PSU fan does all of the work.
    >
    >
    > And at these times, the case is at minimum pressure.

    Yup.

    Tonight we are going to try something different.
    Two stacked 80 mm fans case fans with one going all
    the time at its lowest speed and one hooked up to the
    thermostat. Hopefully that will allow us to maintain
    positive pressure all the time with a fan in reserve for
    when higher air flow is needed. Similarly doubling up
    the PSU exhaust fan is also an option.

    I have read about a cpu cooler that uses two stacked
    fans spinning in opposite directions for higher airflow
    and reduced noise, so we are reasonably confident that
    the stacked fan idea will work.

    >
    >
    >>At -21'C outdoor temp, the case fan spins about 80% of
    >>the time.
    >
    >
    > Interesting. That's one hot box, or airflow is somehow
    > restricted. IIRC, an 80 mm fan moves about 7cfm (depending
    > on speed & restrictions). 7cfm @ 15'C is about 4.3 g/s.
    > Warming air 36C' requires 36 J/g. So that box was putting
    > out 155W. That's quite a bit for a machine at idle.
    >

    Its got a pair of Opty 248's, six 200 GB SATA drives,
    a Radeon 9800 Pro, eight 1 GB PC3200 DIMMs, and sundry
    others, plus heat wasted by PSU inefficiency. Not hard
    to hit 155 W even when idle.

    Measuring at the wall outlet shows a quick climb to 390 W
    when the system boots up, then it settles down to about
    360 W under normal usage (it is primarily used for semi-pro
    video editting). When idle the draw is about 210 W.
  20. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    Ed wrote:
    > On Thu, 06 Jan 2005 07:32:50 GMT, Rob Stow <rob.stow.nospam@shaw.ca>
    > wrote:
    >
    >
    >>We have kludged up something that so far seems to work,
    >>but a real test will have to wait until temperatures
    >>fall again - it is only -21'C tonight.
    >>
    >>We have connected the case fan to a thermostat, with
    >>the exhaust air from the PSU blowing over the thermostat.
    >>The PSU exhaust is no longer vented back outside. The
    >>120 mm case fan has also been replaced with an 80 mm fan
    >>with no increase in RPMs.
    >>
    >>As many air gaps as possible were sealed with tape on the
    >>/inside/ of the case. Around front drive bay covers, for
    >>example. The side panels now feature weatherstripping. :-)
    >>This should dramatically reduce the amount of warm, moist
    >>indoor air that leaks into the case.
    >>
    >>The case fan now only kicks in when the PSU exhaust
    >>convinces the thermostat that the temperature has risen
    >>to 15'C. In case it was not clear, the case fan is used
    >>to draw the cold air in from outside and blow it into
    >>the case. When the case fan is not running, the PSU fan
    >>does all of the work.
    >>
    >>At -21'C outdoor temp, the case fan spins about 80% of
    >>the time.
    >
    >
    > I like the idea, which I had a hole in my PC room wall! ;p

    It is easier than you think to make a hole like that.
    Just be careful to not hit any power lines and to seal
    it *very* well so you don't have moist air leaking into
    the wall where it will condense on the insulation.

    However, consider something else I'd like to try some day:
    Use a water cooling kit but put the radiator outside. That
    way you would only need two 10 mm holes for the coolant
    hoses plus another small hole to provide power to fans
    on the radiator during the warm weather. (Alternatively,
    just move the radiator into the house for the summer.)

    >
    > I'd probably add some desiccant packs (big ones) to the bottom and top
    > of the inside of the case to help keep moisture at a minimum, not sure
    > how much they'd really last or help though with constant moving air.
    >
    > What sort of system do you have,

    Its not mine. It belongs to a friend who does semi-pro
    video editting. I just get to play around with it and
    do weird experiments like this one.

    I built the system for him, so I know ever little thing
    inside it. It is based on the Tyan S2885, with two Opty
    248's, 8 GB of PC3200, six 200 GB SATA drives, a DVD burner,
    and a Radeon 9800 Pro.

    He recently upgraded from Opty 240's so now I've got
    his old processors as the first step towards building
    my own Opty dualie.

    > you doing some massive over clocking or
    > just going for max cool and quite?

    Just cool and quiet. The motherboard has no real
    overclocking options.
  21. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    Rob Stow <rob.stow.nospam@shaw.ca> wrote:
    > it is noticeably noisier than the slower 120 mm fan while
    > still moving less air We figure it is about 7 cfm for 80
    > mm at medium speed vs 10 cfm for 120 mm at slow speed.
    > And the whole point of this scheme is noise reduction.

    OK.

    > Tonight we are going to try something different. Two stacked
    > 80 mm fans case fans with one going all the time at its
    > lowest speed and one hooked up to the thermostat. Hopefully

    Sounds good. Preferably run the downstream fan constantly,
    the upstream on t'stat.

    I guess a measured hole on the cold inlet would be a little bit
    noisier because the fans will run a bit more. I wouldn't worry
    about humidity unless the room has a hot air duct blowing in.
    The PSU exhaust should keep the room positive.

    > that will allow us to maintain positive pressure all the time

    Good.

    > I have read about a cpu cooler that uses two stacked fans
    > spinning in opposite directions for higher airflow and

    Stacked fans work (mor head, same flow). Reverse requires
    blades cut just so.

    > Its got a pair of Opty 248's, six 200 GB SATA drives, a
    > Radeon 9800 Pro, eight 1 GB PC3200 DIMMs, and sundry others,
    > plus heat wasted by PSU inefficiency. Not hard to hit 155
    > W even when idle.

    > Measuring at the wall outlet shows a quick climb to 390
    > W when the system boots up, then it settles down to about
    > 360 W under normal usage (it is primarily used for semi-pro
    > video editting). When idle the draw is about 210 W.

    Wow! That's a pretty loaded box. My guess is that vidcard
    is a pretty big draw.

    -- Robert
  22. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    Robert Redelmeier wrote:
    > Rob Stow <rob.stow.nospam@shaw.ca> wrote:
    >
    >>it is noticeably noisier than the slower 120 mm fan while
    >>still moving less air We figure it is about 7 cfm for 80
    >>mm at medium speed vs 10 cfm for 120 mm at slow speed.
    >>And the whole point of this scheme is noise reduction.
    >
    >
    > OK.
    >
    >
    >>Tonight we are going to try something different. Two stacked
    >>80 mm fans case fans with one going all the time at its
    >>lowest speed and one hooked up to the thermostat. Hopefully
    >
    >
    > Sounds good. Preferably run the downstream fan constantly,
    > the upstream on t'stat.
    >
    > I guess a measured hole on the cold inlet would be a little bit
    > noisier because the fans will run a bit more. I wouldn't worry
    > about humidity unless the room has a hot air duct blowing in.

    It doesn't. It was originally intended to be just a laundry
    room so no provision was made for heating or air conditioning.

    That computer (and a dual Xeon box in the same room) made
    the room is extremely warm in the summer, hence the initial
    attempt to make use of the dryer vent holes for summertime
    heat exhaust. Winter use of those vent holes for computer
    cooling is just a fun experiment.
  23. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    In article <WPeDd.733063$%k.670821@pd7tw2no>, Rob Stow
    <rob.stow.nospam@shaw.ca> writes

    >Measuring at the wall outlet shows a quick climb to 390 W
    >when the system boots up, then it settles down to about
    >360 W under normal usage (it is primarily used for semi-pro
    >video editting). When idle the draw is about 210 W.

    Taking 210W and multiplying by the typical PSU efficiency of 0.7 gives
    147W, which is in the ballpark of the 155W calculated.

    --
    ..sigmonster on vacation
  24. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    Mike Tomlinson wrote:
    > In article <WPeDd.733063$%k.670821@pd7tw2no>, Rob Stow
    > <rob.stow.nospam@shaw.ca> writes
    >
    >
    >>Measuring at the wall outlet shows a quick climb to 390 W
    >>when the system boots up, then it settles down to about
    >>360 W under normal usage (it is primarily used for semi-pro
    >>video editting). When idle the draw is about 210 W.
    >
    >
    > Taking 210W and multiplying by the typical PSU efficiency of 0.7 gives
    > 147W, which is in the ballpark of the 155W calculated.
    >

    Except the 30% PSU /ineffiency/ is turned into heat by
    the PSU, which in turn helps to heat up the cold air - and
    it was the amount of energy needed to heat up that air that
    led Mr. Redelmeier to come up with the 155 W number.
  25. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    GSV Three Minds in a Can wrote:
    >
    > --
    > GSV Three Minds in a Can
    > Outgoing Msgs are Turing Tested,and indistinguishable from human typing.

    Something at a site I was just at used the phrase
    "micturition to windward".

    Why did I immediately start thinking that somewhere in the
    Culture there simply must be a GSV with that name ? D:)
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