Which would disperse heat more efficiently

[DaJe]

Having the CPU fan blowing air away from the heatsink/processor, or blowing air onto it?

[silverdemon]

most of the time blowing air onto it will be cooler, but you should try both, I heard that in some occasions it is more efficient to let the fan 'suck' air away from the heatsink...

[simon275]

Blowing air onto it is always better.

[DaveW]

Blowing air onto it is always better.

Yes, you need to force the air through the fins of the heatsink. The only disadvantage of this is that it then blows the heat onto the motherboard components-a problem that can be avoided with a larger fan, which cools the mobo as well, or a vertical fan like the Zalman, where the fan blows air towards the back of the case.

-Dave

[Razors Edge]

I'll explain it like this

Say there is a bucket of boiling water you want to cool down. So you throw an assload of snow ontop of it. Its only a matter of time till that SNOW melts or gets hot. But if you throw snow at it, with a powerfull air conditioner blowing at it, It will melt slot and last longer.

I mean the heatsink isn't going to keep it cool forever. You need something also to keep the heatsink cool.

[Airbozo]

You could also argue that sucking the air away from the heatsink actually causes air to blow on the heatsink. Most of the time I would go with the heatsinks original setup. There are cases where I would want to suck the air away from the heatsink, but that would depend on what other cooling devices I had in the system.

This sounds like a chance for some testing. Anyone game for setting up a rig to test temperatures of the cpu/mobo/chipset with the fans blowing away from or into the heatsinks?

[dgrmkrp]

i did test this thing a long time ago.. with the Tt V12... sometimes, it was better when reversed... and more silent... but the idea is that you are blowing colder air in the heatsink as opposed to sucking a warmed up air tru the fins... if u need to keep the cpu as cool as possible and still use a "conventional" heatsink.. use a duct to get fresh cold air from outside.. and have the fan blow in the heatsink.. best cooling, a bit noisier..

[Cevinzol]

Blow the air. You want air MOVEMENT over the heat sink.
It has to do with fluid dynamics. Blowing creats a jet of air (cone shapped), while sucking pulls all air equally for any given distance from the nozzles (half sphere). Blowing ensures that most of the air will go through the HS.

Think of it this way... take a shop-vac, try to suck a light object across a table. How close did the nozzle have to be to move it towards you? Now take the same object, reverse the shop-vac (to blow) and notice how much further you can move the object away form the nozzle.

[Silenced_Coyote]

Can't you just stick your hand in front and behind a fan and feel the difference?