only cpu. And you can probably get 3Ghz, not Mhz. 3Ghz = 1000mhz (if you didnt just make a typo).
However, due to the risks of this cooling (I've been doing it a while), If you are asking that question, I think maybe you should try air or watercooling first. With phase change you have to use insulation, grease, seal string, foam, etc, etc. You have to worry about condensation, getting a good mount, etc. It is fun, but there are a lot of hassels with it.
I suggest you do a little more research, head on over to xtremesystems.org/forums to see the best work on earth with phase change, and a great place to learn. That's where I learned everything I know about phase change.