I'm going to have to agree with Gaara. You cannot leave all of the heat transfer up to the compound, yu have to let the metal on metal contact do the transfer. Put a little dot in the middle of the cpu, and strap down the heatsink. The compound is designed to fill into the little grooves where there is no metal on metal contact. When you bolt down the heatsink, the compound will be dispersed accordingly. Where there is metal on metal contact, compound will not go. Where there is no metal on metal contact, compound will go. If you put too much compound on, it will bunch up and not allow the heatsink to sit properly, impeding heat exchange extremely. I once put an even layer of AS5 on my cpu, and strapped my water block to it. My computer was overheating sooo bad. I had the shutdown temp at 149F, but since my computer will not turn off, long story, different story, it would click right back on, start to load windows, overheat, shutdown, click back on, and start the loop over again. It's a vicious cycle. I didnt realize that maybe is was overheating, and i had to clean the AS5 off an reapply it. I did so, and put a dot in the center about the size of a grain of rice. Stays at around 100F.
And get the expensive stuff. Something like this you do not want to cheap out on. It is vital to the healthyness of your cpu. Arctic Silver 5 is the best, a little on the expensive side, but more than worth it.