I am assuming you are using on a intel 775 processor.
Unscrew the 4 clips outside the fins of the stock cooler. They should popup a little bit when they unlock.
Carefullp pry up evenly on the whole heatsink unit. Intel uses those pads with stickum to seal the cpu to the heatsink. A little twisting movement can break the sticky paste loose( very slight back and forth movement).
Now with heatsink off, unclip the 775 processor and pull it out so you can use rubbing alcohol to clean off all traces of the heatsink compound. The processor pulls straight up and out easily as it is just sitting on the pins.
After cleaning the cpu, replace it back in the Motherboard and clamp it down again. If you look the processor can only go in one way. Look for the corner with a triangle cutoff it. match up that with the cpu socket.
Now the 775 procesor has a very large surface for the heatsink to cover so i use 4 BB sized dabs of heatsink compound in a circle around the center of the cpu and use my index finger with a sandwich baggy over it to spread the compound out in a even layer overs the surface. I try to cover the whole area with a thin layer all the way to the edges of the clamp but not enough to cause a buildup ridge at the clamp edges.
Now i will put a veryvery thin layer of compound on the heatsink bottom and then set it on place on the processor. Have just enough compound that you can see a haze of compound. This will ensure good contact with the proc. I now hold the heatsink down with one hand lightly( really just three fingers and my thumb)and don't worry if you have to fumble around with the screws somewhat just as long as you dont have to lift the heatsink off the processor. It will get a good seal. I use a long shank skinny screwdriver to turn the screws the quarter turn necessary to lock them in. Put some pressure down on the screws or you wont get the screw in the socket. Take your time and be somewhat careful. When you get them right and you try twisting slightly with the hand holding the heatsink down it should move very little.
AND your DONE.
Lots of people push all kinds of thermal compound but i have not found where the high priced spread is that much better. One or two degrees is not enough to get me into a lather. I have the ceramic compound simply because i ran across someone selling one ounce tubes of the stuff at discount so i bought 100 tubes. I really don't see where its WAY cooler than the artic silver or even the white zinc oxide standard thermal paste. I've tried them all so i just stick with what i can find.
TIM ? Heres a article on it.http://www.overclockers.com/tips1116/http://www.sidewinde...kticpuhecl.htmlhttp://www.modsynerg...nothermbadz.htm
I hope this helps you.