I will throw in a vote for IC Diamond. Lowered the temps in my EVGA GTX460 5-7C over stock paste. Only needs a 2 hour cure time compared to 200 hours for Arctic Silver 5.
$5.20 at Amazon.
http://www.amazon.com/DIAMOND-CARAT-GRAM-THERMAL-COMPOUND/dp/B0042IEVD8
I wanted to try IC Diamond but I wasn't crazy over how it scratched the heat spreader and heatsink. 4Ryan posted this last week and it was enough to make me not want to use IC Diamond. I know it's not that big of a deal but again I don't like that it scratches also it would void your warranty and make re-selling harder.
The picture below is a P4 2.66mhz socket 478 before.
Using IC Diamond Compound and a Q-Tip for a 2 minute circular rubdown.
And the fastest lapping award goes to? IC Diamond! (Crowd Goes Wild)
Now what you are looking at I just did, with a Q-Tip and IC Diamond in 2 minutes.Intel writing is completely gone and the warranty, if this CPU had one.
Not that you or anyone would do that to your new under warranty CPU, but just proving you can actually lap your CPU with IC Diamond.
What the heck! Below is 5 minutes of fingertip rubbing, you can see the copper beginning to show through in the area of the Q-Tip rubbing.
I was going to lap it all the way to full copper face and ran out of IC Diamond.