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SOLVED How much air temp difference???

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K

Kryten

Guest
Could anyone tell me ROUGHLY how much difference case fans would make to CPU temps.
The fans I have in mind would produce 230 CFM in and 230CFM out + what ever the PSU fan puts out (about 25cfm @ a guess).
I am only trying to guage the temp drop over not having any at all.
 

Nagorak

Senior Member
Joined
Dec 19, 2000
Newby2OC (Apr 10, 2001 02:00 a.m.):
Could anyone tell me ROUGHLY how much difference case fans would make to CPU temps.
The fans I have in mind would produce 230 CFM in and 230CFM out + what ever the PSU fan puts out (about 25cfm @ a guess).
I am only trying to guage the temp drop over not having any at all.

Difference is not going to be enough to justify the extreme noise involved. Think more like 90-100 cfm in and out. Even with only that amout of airflow your case may have better circulation than when you are running caseless. 230 cfm is going to sound like a hurricane, and it's not going to work THAT much better. I'd only even consider that amount of cfm if I were running a dual 1.5 GHz Tbird setup, with a Geforce3 Ultra and 5 SCSI 15000 rpm hard drives thrown in for good measure (all generate extreme heat).

Also, I don't know about your PSU fan, but mine seems REALLY weak. I'd guess 20 cfm maximum and maybe as little as 10-15 cfm.
 

Pat

Member
Joined
Jan 22, 2001
Location
Near St. Louis
I have the Swiftech 462A with the special delta fan. 140cfm in & 125cfm out with Paniflo low noise fans in a full tower case with the Enermax 431 P/S. The Asus A7V13 runs warm. My room temp usually is around 78-80*F. That makes a difference in what your CPU temp is. It can make a -3*C difference when the room was colder this winter.

I sure don't get 30*C cooling like the reviews state because of the starting room temp. My average is 41*C on low fan speed. The delta sounds like a jet engine turned all the way up.

Got to check to see if the bios mod will work on my M/B. It is suppose to drop the CPU temp down by 10*C.

Remember- more air in than out -slight overpressure.

Pat
 

Phil

Senior Member
Joined
Jan 13, 2001
Location
Bolton, UK
most midi tower cases are about 5-6 cf, tower cases are about 10-14cf, so with 230cfm going through it a midi would only have the air in it for about 3-5 seconds (the fans don't push as much as they are rated for in normal curcamstances) and about 6-10 seconds in a tower, this doesn't really give it much time to absorb heat, I would say in a midi case any more than 100cfm (200cfm in total) is a waste unless you have been lazy in the placement, and with a tower I would still only have about 150cfm's worth of fans in and out (300cfm) in total, intake for my case is one 31cfm at the bottom front, a 47cfm at the top front and another 30cfm on the side which is 108cfm in total but probabally only works out at about 90cfm in reality, and for exhaust I have 2 30cfm in my psu (like the enermax setup) a 30cfm fan behind the cpu and a 31 cfm behind that but ducted round the cpu which is only 90cfm out but I prefer a little positive pressure, position and the temp of the air is more important than the amount, as if I put my computer on the floor I get temps 3-4oC cooler, this gives me a motherboard temp of 28oC with my cel 900 with 2.2v (burning in)which I can't better even with the case off and the air in the case is only 24oC with a room temp of 25oC (the temp on the floor is only 20oC)
 
OP
K

Kryten

Guest
Thanks guys this info has been a great help