Comment by jacquesm

Indeed, also, the variation between individual applications is enough to invalidate the results of the number of tests isn't large. It is super easy to mess this up. Too much paste, too little paste, a little bit of grease left behind or maybe a small piece of dirt... A nice way to practice application of paste is to use a piece of glass instead of an aluminum cooler. That will show you exactly what happens between the piece of aluminum and the CPU and it can be quite revealing how hard it is to get a perfect layer without any air trapped. Once you can do it perfectly with the piece of glass you'll be in a much better position to lay down a nice layer with the real thing.