Noctua NH-U12F HSF
 

The exact same 120mm fan is included in the NH-U12F bundle so even before I unpacked the product I already knew this would be a pretty quiet cooling solution. But being quiet isn't enough to be a good CPU cooler, the cooling performance also matters greatly.

http://www.dvhardware.net/review110_noctua_nh_u12f.html