Noctua NH-L9i Low Profile Intel CPU Cooler
 

The Noctua NH-L9i was able to outperform another low profile cooler and the stock Intel cooler, while also being by far the quietest of the three. In addition to keeping the CPU temperature and noise level down, the whole installation process took just a few minutes, and it uses bolts instead of plastic push pins to get the job done right and not just quickly.

http://bigbruin.com/content/nhl9i_1