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How are hsf's supposed to face?

phoeneous

Member
Aug 21, 2003
27
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For years now my hsf has been sucking hot air away from the cpu. Is it supposed to be blowing air onto the cpu?
 

bozo1

Diamond Member
May 21, 2001
6,364
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Depends on the design of the heatsink. Most of them these days blow the air down into the heatsink.
 

phoeneous

Member
Aug 21, 2003
27
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Why? Hot air rises, blowing air onto the cpu will trap heat, wont it? Guess I could try both ways and see what mbm says.
 

pspada

Platinum Member
Dec 23, 2002
2,503
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Blowing in is generally more effective, as it helps the heatsink to disapate heat from the processor.
 

Ecliptic

Golden Member
Oct 15, 2000
1,421
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Originally posted by: phoeneous
Why? Hot air rises, blowing air onto the cpu will trap heat, wont it? Guess I could try both ways and see what mbm says.
ahhhh, isnt you cpu sideways in the tower? at any rate, most blow onto the heatsink, but a few older ones suck air away. Depends on the design. If your heatsink/fan came that way, I would suggest leaving it so.
 

dunkster

Golden Member
Nov 13, 1999
1,473
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There are some system/component considerations that are not obvious.

I ran an Alpha 6045U for a long time on my KR7A board. It is designed to suck air up through the pins.

I installed the 6045U on an 8RDA+ board. After installing an active NB cooler, I noticed an immediate increase of 1C - 2C in CPU temperatures. The heat expelled from the active NB cooler was being injected/sucked into the Alpha, raising CPU temp. Reversing the fan didn't cure the problem, since the cooling efficiency of the 6045 really is better with fan sucking.

I replaced the 6045U with a 900U and a 92mm fan, providing better cooling with acceptable fan noise. One benefit with the 900U/92mm fan combo is that there is an 'overlap' of the fan on two sides due to the non-square design of the 900U. That overlap produces a stream of air on the MOSFETs on one side and surface components and memory on the other side.

Hope this helps!
 

Rankor

Golden Member
Jul 10, 2000
1,667
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0
A good majority of hsf combos have their fans blowing onto the hs. Only exception were/are the cooling solutions from Alpha. There are probably other cooling solutions that suck air away from the hs but the majority blow onto the hs.
 

KF

Golden Member
Dec 3, 1999
1,371
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>Why? ... blowing air onto the cpu will trap heat, wont it?

If you sit behind a fan, are you cooler than when you sit in front? I'd say no. It is for that reason that fans usually blow. The reason is that the air stream is more directed in front than in back. You can fix that with ducting and baffles.
 

Actaeon

Diamond Member
Dec 28, 2000
8,657
20
76
Originally posted by: dunkster
There are some system/component considerations that are not obvious.

I ran an Alpha 6045U for a long time on my KR7A board. It is designed to suck air up through the pins.

I installed the 6045U on an 8RDA+ board. After installing an active NB cooler, I noticed an immediate increase of 1C - 2C in CPU temperatures. The heat expelled from the active NB cooler was being injected/sucked into the Alpha, raising CPU temp. Reversing the fan didn't cure the problem, since the cooling efficiency of the 6045 really is better with fan sucking.

I replaced the 6045U with a 900U and a 92mm fan, providing better cooling with acceptable fan noise. One benefit with the 900U/92mm fan combo is that there is an 'overlap' of the fan on two sides due to the non-square design of the 900U. That overlap produces a stream of air on the MOSFETs on one side and surface components and memory on the other side.

Hope this helps!
What kind of temps do you get with the 900U and the 92mm fan? (Which 92mm fan btw?)

I'm curious, I just ordered a 900U and a 92mm Tornado. Plan on overclocking as well...

Thanks
Jonathan

 

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