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Air pressure help

S

stealthy123

2[H]4U
Joined
Feb 4, 2005
Messages
3,149
I am tweaking my itx system and was wondering if I took my cpu heatsink fan off and instead put a 120mm fan that not only blows on the heatsink but will essentially blow over the entire mobo.

Aren't some cpu coolers dependent on a certain air pressure to work right? I am using the stock llano amd cooler which is just a solid aluminum core with fins coming out, kinda like the old thermoengine coolers minus the copper core. Looking at it, I assume it's not dependent on pressure because of how much space there is between the fins.

I am replacing it with the old am2+ stock amd cooler, and it has a much more dense fin structure so I am concerned it needs the fan right up on it to achieve the air pressure needed to work correctly.

Does anyone know of an article that explains air pressure as it relates to heatsink performace? I know all about pressure inside the case, but I need an article only dealing with heatsinks.

Of course if someone wants to just tell me about it, and explain whether my idea is viable, or if I am confused, I would appreciate it.
 
It would work poorly. The reason you need higher pressure is because lower pressure air will essentially see the fins as a solid block, and won't flow through the fins but instead will flow around the outside of the heatsink (much simplified, but you get the idea). This greatly reduces the surface area you have available for dissipating the heat, and so you will get marginal performance. Modern heatsinks are designed to have the fans located very close to the cooling fins to force the air through the fins.
 
thanks, I thought it was the case, but couldn't be sure of the physics. your solid block analogy was umm, solid.

can I rely on turbulence of an 80 cfm fan in a tiny case to create air pressure? I guess the better question is does turbulence potentially impact air pressure?
 
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You already following basic case practices like sealing all holes or cracks in the case that aren't fan related? I use packing tape to seal all the extra vents or slots so the air is forced to follow the path created by the intake and exhaust fans.
 
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