thermal grease

What is This Goop I Got in My Heatsink Package?

That goop goes between your processor and your heatsink. It (hopefully) has a thermal conductivity at least comparable to the aluminium or copper in your heatsink.

The deal is, no matter how flat it seems your processor and heatsink interface is, there's gonna be little pockets of air that don't conduct heat very well. Heat trapped close to your processor that takes a long time to transfer to the heatsink is a bad thing. So you put the thermal grease in there to keep air out and heat movin' quick.

So, How Do I Put it On?

First, clean both the heatsink and the processor really well. If there's a thermal pad on the heatsink, scrape that bastard off there. When you get that off, you might need to lap the heatsink -- check that writeup for more info. Some sort of alcohol type cleaner will work for the last of the cleaning (don't use the dishsoap). Then put a little bit of the grease on the processor. With modern processors (like the socket 370 / socket a processors) this is going to be a little raised metallic area (around 1 cm²) in the center of the processor's package. You are definitely not going to use that whole blister backage. Now, use something like a clean plastic card (got an old credit card or safeway club card? use that...) to spread the grease evenly and thinly over the surface of the processor. You don't want a whole lot -- the spaces you'll be filling are microscopic. Don't be incredibly concerned, though -- any excess will sort of squish out the sides. Messy but not disasterous. Try to clean any excess off right now. Put the processor in the motherboard, and put the heatsink on. Minimize any twisting action while placing the heatsink, since that will make different areas of the processor have different thicknesses of grease. Ta da. You ought to have much better heatsink performance, especially if you were using something like a thermal pad.