I use the coolermaster H001 heatpipe. It's easy to put on and works better thant stock hsf. The fan is loud so consider that before you buy. I installed a Zalman bracket w/ 92mm fan over it, and a Nexus fan controller. Now I have all my fans at half speed and is very quiet.
Make sure you set up a shut down temp on your Bios, in case the Nexus goes bad. I already had that happen to me, luckuly it' was a case fan and not the hsf fan.