Originally posted by Delirium
I've never done it before, but I read up enough (I think) before hand. I applied paste a little bigger than the size of a pea and smoothed it out with a knife.
With Arctic Silver (the best kind) you use a drop just smaller than a grain of rice on the heat spreader, put the CPU in place, put the heatsink down on top of it without smoothing it at all, rotate it 1 degree in each direction, and put the straps across the heatsink.
If you decide to redo it, make sure you clean both with 99-100% rubbing alcohol, brake cleaner or ArctiClean 2 (do not use any citrus products unless you plan on going over them again with one of the above) and a LINT-FREE cloth; seriously, like a coffee filter. Don't let anything but the thermal paste touch either side; no hair, no dust, and especially no fingerprints.
The layer of thermal paste should be very very thin. As in around 0.003 inches(at least with Arctic Silver; I've never used anything else); hence the reason why you smush the two together instead of spreading it with a knife. By spreading it around, I'm guessing you introduced air pockets and grooves in the paste and/or had some leak over the side of the heat spreader.
In conclusion, ANY old material will cause the interface to get screwey, including air, hair, fingerprints (fingerprints can be thicker than how much paste you need), old paste that wasn't removed with a tough cleaning agent, ect ect. The whole reason for the paste is to fill in the microscopic grooves that manufacturing tools leave behind on the heat spreader and heatsink and make them as if they were one piece of material.
