My new favorite paste for heatsink is the Prolimatech PK2 that came with my Megahalems Rev C which is currently keeping my Intel 6600k over clocked at 4.8 ghz at near water cooled temperatures. (62C at 100% linpack non AVX load) This stuff is super easy to apply I use the pea sized amount in the middle and my temp are awesome, Arctic silver 5 used to be my favorite but honestly the performance of AS5 has been surpassed so much somehow.