Applying thermal paste

I was having a rather heated "discussion" with someone the other day about the correct amount of thermal paste to be applied when mounting your CPU cooler. To some degree, it does depend on the cooler and the type of base it has. Coolers with exposed heat pipes will obviously require a bit more thermal snot to fill up the gaps and creases and channels between the heat pipes. Anyway- the object of thermal grease is to fill the microscopic imperfections in the cooler's base and the top of the CPU to allow for more efficient and complete heat transfer. In a perfect world, we could simply mate metal to metal and get a perfect thermal exchange between the cooler base and the CPU. But we do not live a perfect world, so we need thermal goop. Thermal paste is NOT glue!!! With thermal paste, less is more. Too much thermal paste ends up insulating the CPU and can actually INCREASE the temperature, which is contradictory to what we're trying to accomplish. Here's some screen shots depicting correct (and incorrect) thermal snot applications:

WAY too much thermal snot:


Proper amount of thermal goop:


Amount of thermal interface material BEFORE mounting heat sink:


. . . and after mounting the heatinsk:


The 3rd and 4th shots are a TINY bit heavy on the amount of goop used (IMHO), but this amount is still very acceptable. The amount used in the first picture is FAR too much. In this scenario, I would leave the goop on the CPU, but then clean the base of the cooler completely and mount it again. Doing this would probably be a much more realistic application of thermal snot.

For those of you interested in thermal grease, and the effectiveness of one brand over another, should read this article at Benchmark Reviews where they compare 80 different brands and varieties of thermal compound.

[dlb]
:-D

 

LOL @ thermal snot!:-D I do a thin line about the size of a long grain rice and spread it with a clean credit card or equiv., no accumulated finger grease on there please. There are others that say a blob in the center is OK and the heat will eventually even it out. I obviously take the time to spread it.

 

Another popular way to spread the goop is by wrapping your finger tip with a piece of plastic bag (like a grocery store bag) and then spreading it out that way. On my home PC, my CPU cooler (CoolerMaster Hyper212+) has exposed heat pipes that make direct contact with the CPU (picture of my CPU cooler's base: http://forums.majorgeeks.com/attachment.php?attachmentid=120800&d=1251672108 ). I applied a straight line of compound down the center of each heat pipe, the line of compound was about as thick as a skinny rubber band. I mounted the cooler, then removed it to see how the paste had spread out. It was just about perfect, but I made a mental note of a couple spots that needed a hair more goop (like the thin channels between the heat pipes). Then I cleaned the cooler base, cleaned the CPU, and re-applied the thermal snot, then remounted the cooler. So far, so good. I was playing COD4 last night with HWmonitor running in the background, and my CPU maxed out at only 48C! And I played for about 4 hours!!!

 

Whenever I need to re-apply that stuff, after a thorough cleaning, I apply a small bead about the size of a wooden match head and spread evenly with a single edge razor blade.