CPU cooler fan - blow on to heatsink or away?

  Bailey08787 13:14 07 Sep 2009

Hi there

In the midst of a new build and added a cpu cooler to my cpu last night.

Then it struck me that I wasn't sure whether the fan coupled to the heat sink is either:

a) intended to blow air on to the heatsink to cool it down


b) spin so that it takes hot air away from the heatsink, into the case, out through case exhaust

I'm thinking b), but just thought I'd check

  I am Spartacus 13:18 07 Sep 2009

Blowing down seems to be more effective. It also cools the VRMs as well.

  Ashrich 13:22 07 Sep 2009

I believe they blow on to the heat sink , the other way would only benefit if a cowling was fitted over the heatsink first ( like some Dell desktops )


  Fruit Bat /\0/\ 13:22 07 Sep 2009

mine blows air away from the heatsink.

  Fruit Bat /\0/\ 13:23 07 Sep 2009

and yes it has a cowling

  Bailey08787 15:33 07 Sep 2009

when you say 'down', you mean in the direction of the heatsink yes?

  I am Spartacus 17:26 07 Sep 2009

Yes, blowing through the heatsink.

  interzone55 17:31 07 Sep 2009

You have the fan blowing away.

The heat sink draws heat out away from the CPU, then the fan blows the hot air away from the heat sink...

  GaT7 17:58 07 Sep 2009

Similar post here - Should the cpu fan blow towards or away from it? click here.

I'd say the 'best' way might depend on your setup, case cooling, etc. So it may be worth trying them both to see what works best for you. Use a tool like HWMonitor to check temps click here. G

  DieSse 18:03 07 Sep 2009

The normal direction is down, onto the heatsink. Collers with "comls" are the exception - though I've never actually seen one. All the coolers I've ever seen blow down into the heatsink.

The fins on the heatsink are normally designed to bleed the airstream over nearby components.

There are several designs these days which alternatively have the fan on the side, and blow air "across and through" the fins.

Tome's Hardware did some tests some moons ago, and found there wasn't a huge difference, but blowing down into the fins was slightly more efficient.

  DieSse 18:04 07 Sep 2009

Collers with "comls"

What was that!! - should read Coolers with cowls.

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