Is it better to have a fan blowing on or away from a heatsink?

[DPmaster]

I'm getting a Thermalright SLK-900A for my XP 2600 in a few days. Question is would it be better for the fan to blow on this heatsink or away from it?

 

[sugarkang]

i always thought away was best, but then you'd need a hood.
that way you'd have an add'l exhaust, getting hot air out of the case.
not sure though, so we'll see what the experts say...

 

[ToxicWaste]

Always blow onto the heatsink. I can't ever think of a case when you wouldn't, but someone will probably point one out now...

 

[beatle]

Originally posted by: ToxicWaste
Always blow onto the heatsink. I can't ever think of a case when you wouldn't, but someone will probably point one out now...

Alpha recommends sucking air away. That said, I always had mine blowing down with better results.

 

[optimistic]

Blow. Even with the alpha, blowing onto the hsf yields cooler temps. I think it was amdmb, or some site that figured this out.

 

[xSkyDrAx]

Yep. Blowing on the heatsink will yeild better results.

 

[Corporate Thug]

blowing on

 

[beaconengr]

Why do you guys think that all computers are configured to exhaust air from the hearsink? At least all that ive ever seen. When you blow air from your fan onto the heatsink, you are simply taking the hot air that you should be exhausting from the case and blowing it back onto the heatsink. This makes no sense and all my engineers tell me this is wrong. There is a common misconception that blowing air with a fan cools the air which it does not.

 

[KillaKilla]

Originally posted by: beaconengr
Why do you guys think that all computers are configured to exhaust air from the hearsink? At least all that I've ever seen. When you blow air from your fan onto the heatsink, you are simply taking the hot air that you should be exhausting from the case and blowing it back onto the heatsink. This makes no sense and all my engineers tell me this is wrong. There is a common misconception that blowing air with a fan cools the air which it does not.

I think he means blowing/sucking air for a heatsink/fan, not a case fan. Blowing is always more effective than sucking (IME) with HSFs. For case fans I generally have had the best results with a 3:4 ratio of exhaust:intake fans.

 

[Sid59]

i changed mine to sucking away. i saw a 2C drop going to BLOWING on teh heatsink but it raised my overall case temps.

i also changed it because the dust got into the case and bunnies were forming in the heatsink.

 

[crypticlogin]

In my far-from-expert opinion, screw what the manufacturer SAYS to do -- do what works best for YOUR setup.

 

[1966]

Originally posted by: tenchim
In my far-from-expert opinion, screw what the manufacturer SAYS to do -- do what works best for YOUR setup.

Yup, agreed.

 

[Sid59]

indeed. so far, since i replaced the crappy generic grease and applied AS3 and let it burn in for 2 weeks now, my temps are about 7C lower.