Apple uses a glob of green goo on the CPU, and nothing but thermal pads on the GPU and etc. its kind of a pain to clean off, but once you do get it clean and add arctic silver an odd downside is that the fan(s) start to spin more often as a greater amount of heat is being transferred from the CPU to the heatsink, rather than just being trapped in the CPU. its a trade-off i'm willing to live with, however.