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Mounting a fan the wrong way on a HS

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Stupid Boy

Jan 17, 2004
Scarsdale, NY
I only have cr*p heatsinks where I am now, so I can't try this for a couple weeks.

How much warmer does the CPU normally get when one mounts the fan on a SP-97 such that the fan blows air away from the heatsink than the CPU gets when I mount the fan correctly?

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May 22, 2004
Gainesville, FL / Frankfurt Germany
There has been a lot of tests using the fan in a pull configuration. It can be very efficient, as in watercooling, the Radiator (much like a big heatsink) prefers to have air pulled through it. Correct me if I am wrong, but I have heard that axial fans are actually better at pulling than they are at pushing air through something restrictive.
The problem that arises is however, that if you were to invert your fan on the SP-97, the suction would not reach the hotter air near the base of the HS. Thus reducing efficiency.
You can make this work by cloaking your HS's sides while leaving a space at the base. You would then also have to mount the fan on a shroud to get rid of most of the dead spot.
This would be an interesting experiment I think, anyone care to comment?


Sep 26, 2003
Test it when you get your components , test and see what results you get with it either way...Individual results may vary.:D

a c i d.f l y

Apr 1, 2003
Austin, TX, USA
Generally speaking from when I have tested this -- I get about 5-7°C warmer. Sometimes more. Haven't tried with a higher powered fan, but every 25-40cfm I've used have always shown difficiency, regardless of the heatsink I've used.

It must be efficient in some ways, as that is how car radiators are designed... at a high enough velocity/cfm, you can actually cause the air to supercool, lower than ambient. It is clever science... I wish I knew the term.. a large heatsink, something that would hold a 120mm (possibly the xp-120) connected to a shroud (120-92 or 120-80), sucking air, might be quite efficient.

Interesting, nontheless.



Oct 24, 2003
Buffalo, NY
I've tried this with my sf2 on my sp94. At load, cpu goes from 41 to 46 C, system goes from 30 to 26 C. So, I gained system temperatures while sacraficing cpu temperatures. There's a recent thread in this forum where a guy used 2 80mm fans in a pull configuration and had noticedable gains, primarily because the edge of each fan was over the center of the heatsink. Thus, the fans' deadspots were on the edge of the heatsink.