Processor Fan - Suck Or Blow

  [DELETED] 09:50 27 Aug 2003

Should the fan on top of the Heatsink for a Processor suck the air through the Heatsink and then into the case


blow air from the case down into the Heatsink so it flows out the Heatsink sides??


no difference?

Just curious as I've got to mount a new fan on an old Heatsink and i just wondered...

  [DELETED] 09:52 27 Aug 2003

the hot air from heatsink into case. An extractor fan on the rear of the case as near as possible to heatsink fan, will then take it away.


  [DELETED] 09:55 27 Aug 2003

Also, of course, a front case fan sucking in cool air is a good idea too. The air flow should be unrestricted and go from front to back, across CPU, Graphics card etc. etc.


  [DELETED] 10:02 27 Aug 2003

This is an old PC so Processor fan is fine.

Thats what i thought but the original had the fan blowing into the heatsink....

  [DELETED] 10:04 27 Aug 2003

My fan takes cool air from the case down onto the heatsink I also have a case fane blowing air from outside directly onto the heatsink & processor and two othe fans drawing air into the case and two extracting air from the case.

  [DELETED] 10:16 27 Aug 2003

Well the original blew down in the the heatsink.

The new fans will only mount blowing down too (screws won't reach other way up) Its a Win98 used by a 10 year old. No internet of games etc.

I'll mount it blowing in to the heatsink as a) i can see that this would "blow the heat out" more effectively that "sucking it out" - which is more effective over distance? Hair dryer or a hoover... and b) the screws don't reach when sucking so it falls off!!!!!!!

  [DELETED] 10:18 27 Aug 2003

Oh well! Trust me to get it the wrong way round. <grin>

Should mention I have twin fans either side of my heatsink - and yes, they must suck in cold air and blow across the heatsink.


  [DELETED] 21:50 27 Aug 2003

PSU fans should blow air across the heatsink. As stated above the fan is then handing cool air from inside the case not warm air off the CPU heat sink.

Cool air is denser than warm air.

Dense air has a greater mass than warm air per unit volume.

The greater the mass flow rate, the greater the heat transfer (cooling effect).

Nuff said?

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