thermal paste stategies

skimzzz

Distinguished
Nov 18, 2001
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I have been using Arctic Silver II on a couple of CPUs, and have found out that unless you use a really thin coat (where you can't see the silver any more), the CPU will overheat. I read the instructions on their website and even some reviews on other web sites, and they all seem to recommend using a thicker coat (where you can see the silver). Don't know why this doesn't work for me.

Anyone else come up with strategies for putting on thermal pastes?
 

silverpig

Splendid
Dec 31, 2007
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You aren't supposed to use that much. Actually, the ideal situation would be to not use any thermal paste at all. What you want is to have a perfectly flat surface on your cpu and heatsink, and have nothing in between. This would lead to the best heat transfer. But, because neither of those surfaces are perfect, air gaps form, and the air insulates the cpu, and keeps the heat in. What thermal paste does is it forces the air out of these gaps, and takes away this insulating effect. However, the transfer of heat from cpu to paste to heatsink is not as good as the transfer from cpu to heatsink, but it is better than cpu to air to heatsink. So you really want to have as much of the surface of the heatsink touching as much of the surface of the cpu as possible, with the paste just filling in the tiny air gaps.

A good thing to do is to lap the surface of your heatsink. I take some 400 grit emery paper and a piece of glass to get the bottom of the heatsink flat, then use 600 followed by 800 grit paper to give it a slightly better surface. I then polish the surface with 1200 grit paper, then redo the 1200 grit finish with some WD-40. This should leave you with a mirror shine on your heatsink. Add a very very thin coat of thermal paste, and you'll be set. The lapping on my heatsink dropped my temps by about 4 degrees C, and some people have gotten drops as high as 5 or 6.

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