I have been slowly collecting parts from old computers, and throwing away the bad ones (power supplies and cases are the hardest to get a hold of) and being curious I had removed the heatsinks from a P4, PD, and an Athlon X2 and switched the Pentiums between a two motherboards[I probably will keep them in the motherboards they came with], My plan is to hopefully build a no cost NAS server, and a free HTPC with the Athlon. My question is, do I need to clean the parts and replace the thermal compound, or can I just keep the heatsinks on the processors? And how much would that cost me?