# Alt: CFM calculator to get rid of HEAT (TDP or WATTS)

Skybuck Flying
Guest
Posts: n/a

 05-18-2011, 09:56 AM
miss it ! =D

Important topic ! =D

Hello,

I'm curious if it's possible to build a powerfull PC/iCore/GPU/Cuda PC
without getting into heat problems !

For example CPU has about 30 TDP (which is close to watts, otherwise find
watts listing) and GPU could have as much as 200 to 300 TDP (watts) (top
model for maximum bandwidth).

Additional watts for memory( 20 watt ? just guessing ) /motherboard (10
watt ?)/4 harddisk (60 watt*4=240)

Let's say 800 watts.

How much CFM would be needed to get rid of all that heat ?!?

A CFM heat (PC) calculator would be most handy... maybe somebody can
make/program it.

What would be good formula's to use ?!?

Bye,
Skybuck =D

Paul
Guest
Posts: n/a

 05-18-2011, 10:12 AM
Skybuck Flying wrote:
> miss it ! =D
>
> Important topic ! =D
>
> Hello,
>
> I'm curious if it's possible to build a powerfull PC/iCore/GPU/Cuda PC
> without getting into heat problems !
>
> For example CPU has about 30 TDP (which is close to watts, otherwise find
> watts listing) and GPU could have as much as 200 to 300 TDP (watts) (top
> model for maximum bandwidth).
>
> Additional watts for memory( 20 watt ? just guessing ) /motherboard (10
> watt ?)/4 harddisk (60 watt*4=240)
>
> Let's say 800 watts.
>
> How much CFM would be needed to get rid of all that heat ?!?
>
> A CFM heat (PC) calculator would be most handy... maybe somebody can
> make/program it.
>
> What would be good formula's to use ?!?
>
> Bye,
> Skybuck =D
>

CFM = 3.16 * Watts / Delta_T_degrees_F

Say room temperature is 72F, case air temperature target is 90F,
computer watts is 200 watts.

CFM = 3.16 * 200 / (90 - 72) = 35CFM

You can get around three times that airflow rating from a fan like this,
but you don't want to be sitting next to this. The fan draws
12V @ 1A and should not be connected to the motherboard header.
You can run this off a Molex drive connector.

http://www.circuittest.com/cfa121203...l-bearing.html

DDR3 memory DIMMs are around 2W. Hard drives are less than 12W. Your
800W number needs to be reworked.

Paul

Skybuck Flying
Guest
Posts: n/a

 05-18-2011, 10:15 AM
Hmmm... could be really simple...

Wikipedia shows conversion chart:

http://en.wikipedia.org/wiki/Convers...heat_flow_rate

1 atmosphere-cubic foot per minute = 47.820 074 682 24 W

Which is probably close to 48 Watts.

But this is atm-cfm and not cfm hmm... not sure if that is same thing... but
for now I'll go with it

So (800 * 60) / 48 = 1000 CFM needed ! =D

Let's see if antec case is sufficient lol:

http://www.antec.com/pdf/manuals/1200_EN%20manual.pdf

So there is no way that the antec 1200 case would be able to cool such a
system sufficiently.

Yes perhaps the graphics card would output a little bit of air as well...
but it's waaayyyy too little.

And this manual probably assumes at maximum operating fan speed... so let's
divide 240 by 2 is 120 CFM... and let's divide it one more time because of
dust is only 60 CFM.

Yeah...

Well it's pretty clear where this is going:

OVERHEAT DAMAGE ! =D

Bye,
Skybuck

"Skybuck Flying" <(E-Mail Removed)> wrote in message
news:3319\$4dd397df\$54192c06\$(E-Mail Removed)1.nb. home.nl...
> some miss it ! =D
>
> Important topic ! =D
>
> Hello,
>
> I'm curious if it's possible to build a powerfull PC/iCore/GPU/Cuda PC
> without getting into heat problems !
>
> For example CPU has about 30 TDP (which is close to watts, otherwise find
> watts listing) and GPU could have as much as 200 to 300 TDP (watts) (top
> model for maximum bandwidth).
>
> Additional watts for memory( 20 watt ? just guessing ) /motherboard (10
> watt ?)/4 harddisk (60 watt*4=240)
>
> Let's say 800 watts.
>
> How much CFM would be needed to get rid of all that heat ?!?
>
> A CFM heat (PC) calculator would be most handy... maybe somebody can
> make/program it.
>
> What would be good formula's to use ?!?
>
> Bye,
> Skybuck =D
>
>
>
>
>

Skybuck Flying
Guest
Posts: n/a

 05-18-2011, 10:23 AM
It might seem "we computer people" are getting fooled/scammed by
specifications ((unrealistic)CFM).

I sure hope that's not the case because then all of your calculations are
wrong...

and with "your" I mean everybody that used CFM.

You might want to read up on this stuff:

http://en.wikipedia.org/wiki/Actual_...eet_per_minute

"real cfm"

For now after a quick glance I am thinking my atmosperic calculations might
actually be closer to the truth

Time will tell ! =D

Bye,
Skybuck.

"Paul" <(E-Mail Removed)> wrote in message
news:ir0621\$kvj\$(E-Mail Removed)...
> Skybuck Flying wrote:
>> some miss it ! =D
>>
>> Important topic ! =D
>>
>> Hello,
>>
>> I'm curious if it's possible to build a powerfull PC/iCore/GPU/Cuda PC
>> without getting into heat problems !
>>
>> For example CPU has about 30 TDP (which is close to watts, otherwise find
>> watts listing) and GPU could have as much as 200 to 300 TDP (watts) (top
>> model for maximum bandwidth).
>>
>> Additional watts for memory( 20 watt ? just guessing ) /motherboard (10
>> watt ?)/4 harddisk (60 watt*4=240)
>>
>> Let's say 800 watts.
>>
>> How much CFM would be needed to get rid of all that heat ?!?
>>
>> A CFM heat (PC) calculator would be most handy... maybe somebody can
>> make/program it.
>>
>> What would be good formula's to use ?!?
>>
>> Bye,
>> Skybuck =D
>>

>
> CFM = 3.16 * Watts / Delta_T_degrees_F
>
> Say room temperature is 72F, case air temperature target is 90F,
> computer watts is 200 watts.
>
> CFM = 3.16 * 200 / (90 - 72) = 35CFM
>
> You can get around three times that airflow rating from a fan like this,
> but you don't want to be sitting next to this. The fan draws
> 12V @ 1A and should not be connected to the motherboard header.
> You can run this off a Molex drive connector.
>
> http://www.circuittest.com/cfa121203...l-bearing.html
>
> DDR3 memory DIMMs are around 2W. Hard drives are less than 12W. Your
> 800W number needs to be reworked.
>
> Paul

Skybuck Flying
Guest
Posts: n/a

 05-18-2011, 10:35 AM
Another nice website:

http://www.truetex.com/aircompressors.htm

Mentions pressure must be added to the equation of "CFM"

Manual of antec1200 mentions "static pressure".

(it's something like 0.something ! yeah ! lol)

Gonna look that up

Bye,
Skybuck.

Skybuck Flying
Guest
Posts: n/a

 05-18-2011, 10:48 AM
More interesting stuff:

http://extension.usu.edu/files/publi...ry_Vent_03.pdf

Bye,
Skybuck.

Rob
Guest
Posts: n/a

 05-18-2011, 11:03 AM
On 18/05/2011 11:23, Skybuck Flying wrote:
> It might seem "we computer people" are getting fooled/scammed by
> specifications ((unrealistic)CFM).
>
> I sure hope that's not the case because then all of your calculations are
> wrong...
>
> and with "your" I mean everybody that used CFM.
>
> You might want to read up on this stuff:
>
> http://en.wikipedia.org/wiki/Actual_...eet_per_minute
>
> "real cfm"
>
> For now after a quick glance I am thinking my atmosperic calculations might
> actually be closer to the truth
>
> Time will tell ! =D
>
> Bye,
> Skybuck.
>
> "Paul"<(E-Mail Removed)> wrote in message
> news:ir0621\$kvj\$(E-Mail Removed)...
>> Skybuck Flying wrote:
>>> some miss it ! =D
>>>
>>> Important topic ! =D
>>>
>>> Hello,
>>>
>>> I'm curious if it's possible to build a powerfull PC/iCore/GPU/Cuda PC
>>> without getting into heat problems !
>>>
>>> For example CPU has about 30 TDP (which is close to watts, otherwise find
>>> watts listing) and GPU could have as much as 200 to 300 TDP (watts) (top
>>> model for maximum bandwidth).
>>>
>>> Additional watts for memory( 20 watt ? just guessing ) /motherboard (10
>>> watt ?)/4 harddisk (60 watt*4=240)
>>>
>>> Let's say 800 watts.
>>>
>>> How much CFM would be needed to get rid of all that heat ?!?
>>>
>>> A CFM heat (PC) calculator would be most handy... maybe somebody can
>>> make/program it.
>>>
>>> What would be good formula's to use ?!?
>>>
>>> Bye,
>>> Skybuck =D
>>>

>>
>> CFM = 3.16 * Watts / Delta_T_degrees_F
>>
>> Say room temperature is 72F, case air temperature target is 90F,
>> computer watts is 200 watts.
>>
>> CFM = 3.16 * 200 / (90 - 72) = 35CFM
>>
>> You can get around three times that airflow rating from a fan like this,
>> but you don't want to be sitting next to this. The fan draws
>> 12V @ 1A and should not be connected to the motherboard header.
>> You can run this off a Molex drive connector.
>>
>> http://www.circuittest.com/cfa121203...l-bearing.html
>>
>> DDR3 memory DIMMs are around 2W. Hard drives are less than 12W. Your
>> 800W number needs to be reworked.
>>
>> Paul

Paul's calculation is correct. He knows what he is talking about.
--
Rob

Paul
Guest
Posts: n/a

 05-18-2011, 11:22 AM
Rob wrote:
> On 18/05/2011 11:23, Skybuck Flying wrote:
>> It might seem "we computer people" are getting fooled/scammed by
>> specifications ((unrealistic)CFM).
>>
>> I sure hope that's not the case because then all of your calculations are
>> wrong...
>>
>> and with "your" I mean everybody that used CFM.
>>
>> You might want to read up on this stuff:
>>
>> http://en.wikipedia.org/wiki/Actual_...eet_per_minute
>>
>> "real cfm"
>>
>> For now after a quick glance I am thinking my atmosperic calculations
>> might
>> actually be closer to the truth
>>
>> Time will tell ! =D
>>
>> Bye,
>> Skybuck.
>>
>> "Paul"<(E-Mail Removed)> wrote in message
>> news:ir0621\$kvj\$(E-Mail Removed)...
>>> Skybuck Flying wrote:
>>>> some miss it ! =D
>>>>
>>>> Important topic ! =D
>>>>
>>>> Hello,
>>>>
>>>> I'm curious if it's possible to build a powerfull PC/iCore/GPU/Cuda PC
>>>> without getting into heat problems !
>>>>
>>>> For example CPU has about 30 TDP (which is close to watts, otherwise
>>>> find
>>>> watts listing) and GPU could have as much as 200 to 300 TDP (watts)
>>>> (top
>>>> model for maximum bandwidth).
>>>>
>>>> Additional watts for memory( 20 watt ? just guessing )
>>>> /motherboard (10
>>>> watt ?)/4 harddisk (60 watt*4=240)
>>>>
>>>> Let's say 800 watts.
>>>>
>>>> How much CFM would be needed to get rid of all that heat ?!?
>>>>
>>>> A CFM heat (PC) calculator would be most handy... maybe somebody can
>>>> make/program it.
>>>>
>>>> What would be good formula's to use ?!?
>>>>
>>>> Bye,
>>>> Skybuck =D
>>>>
>>>
>>> CFM = 3.16 * Watts / Delta_T_degrees_F
>>>
>>> Say room temperature is 72F, case air temperature target is 90F,
>>> computer watts is 200 watts.
>>>
>>> CFM = 3.16 * 200 / (90 - 72) = 35CFM
>>>
>>> You can get around three times that airflow rating from a fan like this,
>>> but you don't want to be sitting next to this. The fan draws
>>> 12V @ 1A and should not be connected to the motherboard header.
>>> You can run this off a Molex drive connector.
>>>
>>> http://www.circuittest.com/cfa121203...l-bearing.html
>>>
>>>
>>> DDR3 memory DIMMs are around 2W. Hard drives are less than 12W. Your
>>> 800W number needs to be reworked.
>>>
>>> Paul

>
> Paul's calculation is correct. He knows what he is talking about.

That's the only equation I know of, off hand. I'm not a thermal engineer,
and cribbed that off a web page that detailed how to put a computer
into an enclosure, and ensure it got enough cooling air. I expect
there is some room for using pressure curves for the fan, but I
don't know the first thing about that. I had an engineer at work,
who used to do that part for us. When you work in a big company,
you're generally "stuck in a silo".

Paul

Skybuck Flying
Guest
Posts: n/a

 05-18-2011, 11:25 AM
More interesting stuff, in case my calculations are off, but pressure does
play a roll as does temperature of air:

http://en.wikipedia.org/wiki/Standar...eet_per_minute

Bye,
Skybuck.

Skybuck Flying
Guest
Posts: n/a

 05-18-2011, 11:33 AM
Really interesting stuff:

http://en.wikipedia.org/wiki/Heat_transfer

Getting down to basics now lol... getting down to the core of it ! =D

Bye,
Skybuck.

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