rec.autos.simulators

by **SLCsurf** » Sun, 12 Dec 1999 04:00:00

Hello,
I'm going to build a PIII computer for sims racing and flying. I found a
company on the internet (www.computersdivine.com) that adds in and out cooling
fans to several different cases. I called and talked to them and they
recommended the Alaska Midtower ATX, with 300 watt power and 7 fans is priced
at $150. The newest case they modify has 10 fans for $175. You can also have
them modify an Enlight case for about the same price. Anyone bought one of
their cases? Your thoughts....or other cases available that I don't have to
modify myself.
Thanks,
Steve

by **Lutrel** » Sun, 12 Dec 1999 04:00:00

Seven fans sounds very noisy and a bit overkill. I bought a digital
indoor/outdoor thermometer for $15.00 to see how hot my case gets. Its a P2 350
with two V2 in SLI.
The case gets to about 104 deg F, but the V2 with fans get to 140 deg. F.
With a $10.00 "blower" type fan from Radio Shack drawing air from the V2 cards
and forcing air out the back vents, the V2 card get to 125 deg F and case temp
is about 98 deg. F. at 70 deg F room temp. I would see if you have problems and
check the temp and then see if you need extra fans.
Lutrell

>Hello,
>I'm going to build a PIII computer for sims racing and flying. I found a
>company on the internet (www.computersdivine.com) that adds in and out cooling
>fans to several different cases. I called and talked to them and they
>recommended the Alaska Midtower ATX, with 300 watt power and 7 fans is priced
>at $150. The newest case they modify has 10 fans for $175. You can also have
>them modify an Enlight case for about the same price. Anyone bought one of
>their cases? Your thoughts....or other cases available that I don't have to
>modify myself.
>Thanks,
>Steve

by **(Raymond, ACT LABS** » Tue, 14 Dec 1999 04:00:00

Hello,
Those fans seem like a bit overkill. I have a pretty "tweaked" system
and have been able to drop case temperaturefrom 45 degrees C to 34
degrees C by just adding a couple of fans.
With case thermal dynamics, there are two main things you want to
consider. Case temperature and component temperature.
With decreasing case temperature, the most important thing is air
flow. Basically, you want cool air sucked in from the bottom and warm
air expelled at the top. The problem is that the new ATX form factor
lists the specs for the power supply fan (at the top) to blow air in
and onto the CPU. You need to reverse this so that air blows out at
the top. This is very easy to do.
I have a standard case and have just added a case fan at the front
(pulling in), a Radio Shack blower at the top (out), some hard drive
fans in the front, top and one slot fan. Basically, you want to
ensure that the total volume of air being moved in is the same as the
volume of air moving out. Unless you are thinking of toasting bread
in your case, you probably don't need all that cooling.

Raymond
ACT LABS

by **Goy Larse** » Tue, 14 Dec 1999 04:00:00

> Hello,
> Those fans seem like a bit overkill. I have a pretty "tweaked" system
> and have been able to drop case temperaturefrom 45 degrees C to 34
> degrees C by just adding a couple of fans.
> With case thermal dynamics, there are two main things you want to
> consider. Case temperature and component temperature.
> With decreasing case temperature, the most important thing is air
> flow. Basically, you want cool air sucked in from the bottom and warm
> air expelled at the top. The problem is that the new ATX form factor
> lists the specs for the power supply fan (at the top) to blow air in
> and onto the CPU. You need to reverse this so that air blows out at
> the top. This is very easy to do.

snip

Uhm, I *think* you are wrong about the PSU fan blowing INTO the case,
none of the cases we've used in our company has had a PSU fan blowing
into the case, that would be pretty stupid if they did.....

Beers and cheers
(uncle) Goy

by **(Raymond, ACT LABS** » Wed, 15 Dec 1999 04:00:00

Hello,
Actually, I did not make any inferences to the cases you have used.
What I did say was that Intel's ATX form factor spec sheets call for
the power supply fan to blow into the case. If you don't believe me,
you can visit Intel's web site.

Raymond
ACT LABS

>> Hello,
>> Those fans seem like a bit overkill. I have a pretty "tweaked" system
>> and have been able to drop case temperaturefrom 45 degrees C to 34
>> degrees C by just adding a couple of fans.
>> With case thermal dynamics, there are two main things you want to
>> consider. Case temperature and component temperature.
>> With decreasing case temperature, the most important thing is air
>> flow. Basically, you want cool air sucked in from the bottom and warm
>> air expelled at the top. The problem is that the new ATX form factor
>> lists the specs for the power supply fan (at the top) to blow air in
>> and onto the CPU. You need to reverse this so that air blows out at
>> the top. This is very easy to do.
>snip

>Uhm, I *think* you are wrong about the PSU fan blowing INTO the case,
>none of the cases we've used in our company has had a PSU fan blowing
>into the case, that would be pretty stupid if they did.....

>Beers and cheers
>(uncle) Goy

Raymond
ACT LABS

by **ssra** » Wed, 15 Dec 1999 04:00:00

>Hello,
>Actually, I did not make any inferences to the cases you have used.
>What I did say was that Intel's ATX form factor spec sheets call for
>the power supply fan to blow into the case. If you don't believe me,
>you can visit Intel's web site.

>Raymond
>ACT LABS
>>snip

>>Uhm, I *think* you are wrong about the PSU fan blowing INTO the case,
>>none of the cases we've used in our company has had a PSU fan blowing
>>into the case, that would be pretty stupid if they did.....

>>Beers and cheers
>>(uncle) Goy

Unfortunaltly you are right about the ATX "design".
The first thing I do when ever i build a new system is swap the fan
around, out here in the Real world doing that results in a 5-10F drop
in temp
The design monkeys at Intel-M$FT etc. seem to have never left a lab
where temps fluctate above the 50-60F they are used to.

For Goy if your cases are ATX and are pushing air then whomever built
them for you flipped the fan posittion (not hard to do)

Raymond nice to see you post.. but wow let up a sec it looks like an
Act Labs group <G>

by **Goy Larse** » Wed, 15 Dec 1999 04:00:00

> Hello,
> Actually, I did not make any inferences to the cases you have used.
> What I did say was that Intel's ATX form factor spec sheets call for
> the power supply fan to blow into the case. If you don't believe me,
> you can visit Intel's web site.

I just did, and although it seems at first glance that you may be right,
I think this is a case of bad "wording" on Intel's part, I think what
they are trying to say is that the ATX PSU air intake must be situated
on the "floor" rather than on the side wall as it was in the "AT days",
anything else would be rather silly don't you think ?

Although little surprises me when it comes to computer designs these
days, Intel can't be that stupid ? :-)

Beers and cheers
(uncle) Goy

by **Steve Ferguso** » Wed, 15 Dec 1999 04:00:00

: Whatever the wording, the early ATX cases that "some" computer manufacturers
: were using had the power supply fan drawing air into the case, the power
: supply would heat up the air, and then blow the hot air onto the CPU and
: motherboard.  I bought a PII-300 from Comtrade two years ago and it
: came with this silly "design" flaw.  I had constant lockups due to
: overheating, tried some case fans with blower, etc... and finally resorted
: to reversing the fan in the power supply.  I STILL can't understand
: how someone can build a computer that way and not realize the err of their
: ways.  I argued with a few Comtrade techs about it, and they could
: never give me a straight answer or "see" the problem with this design. 

I have come across several engineers who insist that there is no
difference between "pulling" and "pushing" air out of or into the case of
a variety of electronic components. I have also gotten into big arguments
about what exactly a fan does (is it a constant mass or a constant volume
device). When I was working in the design of off-gas loops for
steelmaking plants, we always had trouble explaining why the placement of
a blower in the loop, and not just the size of the blower, was important.

Stephen

by **Goy Larse** » Wed, 15 Dec 1999 04:00:00

> : Whatever the wording, the early ATX cases that "some" computer manufacturers
> : were using had the power supply fan drawing air into the case, the power
> : supply would heat up the air, and then blow the hot air onto the CPU and
> : motherboard.  I bought a PII-300 from Comtrade two years ago and it
> : came with this silly "design" flaw.  I had constant lockups due to
> : overheating, tried some case fans with blower, etc... and finally resorted
> : to reversing the fan in the power supply.  I STILL can't understand
> : how someone can build a computer that way and not realize the err of their
> : ways.  I argued with a few Comtrade techs about it, and they could
> : never give me a straight answer or "see" the problem with this design. 

In that case I stand corrected, still think it's silly though :-)

And, I've personally built well over 500 PC's and never come across this
design, so I guess most case manufacturers realized this fairly early,
amazing....

Beers and cheers
(uncle) Goy

by **(Raymond, ACT LABS** » Thu, 16 Dec 1999 04:00:00

Hello Goy,
Well I agree that Intel really mucked up on their "design." It has
baffled myself and many other overclockers as to why Intel would
design air flow from back top to front bottom. Didn't we all learn in
elementary school that hot air rises? I believe what Intel was trying
to achieve was to increase airflow onto the CPU. Unfortunately, they
failed to realize that this was only benficial so long as the power
supply didn't heat up (not possible of course).
Glad to see that I am not the only one obsessive enough to open up my
power supply and reverse the fan.

Raymond

>> : Whatever the wording, the early ATX cases that "some" computer manufacturers
>> : were using had the power supply fan drawing air into the case, the power
>> : supply would heat up the air, and then blow the hot air onto the CPU and
>> : motherboard.  I bought a PII-300 from Comtrade two years ago and it
>> : came with this silly "design" flaw.  I had constant lockups due to
>> : overheating, tried some case fans with blower, etc... and finally resorted
>> : to reversing the fan in the power supply.  I STILL can't understand
>> : how someone can build a computer that way and not realize the err of their
>> : ways.  I argued with a few Comtrade techs about it, and they could
>> : never give me a straight answer or "see" the problem with this design. 

>In that case I stand corrected, still think it's silly though :-)

>And, I've personally built well over 500 PC's and never come across this
>design, so I guess most case manufacturers realized this fairly early,
>amazing....

>Beers and cheers
>(uncle) Goy

Raymond
ACT LABS

by **Eldre** » Fri, 17 Dec 1999 04:00:00

>: Whatever the wording, the early ATX cases that "some" computer
>manufacturers
>: were using had the power supply fan drawing air into the case, the power
>: supply would heat up the air, and then blow the hot air onto the CPU and
>: motherboard.  I bought a PII-300 from Comtrade two years ago and it
>: came with this silly "design" flaw.  I had constant lockups due to
>: overheating, tried some case fans with blower, etc... and finally resorted
>: to reversing the fan in the power supply.  I STILL can't understand
>: how someone can build a computer that way and not realize the err of their
>: ways.  I argued with a few Comtrade techs about it, and they could
>: never give me a straight answer or "see" the problem with this
>design. 

>I have come across several engineers who insist that there is no
>difference between "pulling" and "pushing" air out of or into the case of
>a variety of electronic components. I have also gotten into big arguments
>about what exactly a fan does (is it a constant mass or a constant volume
>device). When I was working in the design of off-gas loops for
>steelmaking plants, we always had trouble explaining why the placement of
>a blower in the loop, and not just the size of the blower, was important.

>Stephen

If we're not talking about the power supply heating the air first(IOW, if
that's not a factor), what exactly IS the difference? You're still getting
cool air coming in one end, and warm air going out the other end...?

Eldred
--
Tiger Stadium R.I.P. 1912-1999
Own Grand Prix Legends? Goto http://gpl.gamestats.com/vroc

Never argue with an idiot. He brings you down to his level, then beats you
with experience...
Remove SPAM-OFF to reply.

by **Steve Ferguso** » Fri, 17 Dec 1999 04:00:00

:>I have come across several engineers who insist that there is no
:>difference between "pulling" and "pushing" air out of or into the case of
:>a variety of electronic components. I have also gotten into big arguments

: If we're not talking about the power supply heating the air first(IOW, if
: that's not a factor), what exactly IS the difference? You're still getting
: cool air coming in one end, and warm air going out the other end...?

Depending on the case design and fan design, you can have very different
airflow characteristics over the components when you are "pulling" the air
rather than "pushing" the air. this can influence the transfer of heat
from the component to the airstream. A lot of the relationships are
empirical, so quite often it's not obvious why components are overheating
with a small change in design. In the extreme case, upstream air could be
almost laminar (smooth flow, very little mixing) while downstream air
could be turbulent (lots of mixing). This depends on the design of the
fan inlet and outlet, and the flow rate. It's all subtle stuff.

Stephen

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