The Thermalright Ultra 120 is an immense heatsink that is designed to cool without needing a fan.  It even manages to out perform the stock Intel cooler, while generating no noise.  The interesting trick with this heatsink is that you can easily attach a 120mm fan, and get incredible cooling power.  Head to AnandTech for a look at the performance of this powerful cooler.
“Readers who tenaciously seek silence in their PC will probably recognize the Thermalright Ultra 120. It is not exactly the same heatsink, but it is similar in appearance to the HR-01 fanless cooler introduced by Thermalright in late 2005. That cooler shipped for AMD only, as we were still in the hot Intel Prescott days. Adapters were introduced later to allow HR-01 to mount on newer sockets, and HR-01 is still in the Thermalright product line as a fanless cooler.

However, there is no way to even mount a fan on the early versions of HR-01, so its appeal was limited to users seeking silence at around stock speeds. Overclockers really had little use for the HR-01. Thermalright recognized that a cooler designed to perform well with no fan could be very attractive to overclockers if there were some means of active cooling, and so the Ultra 120 was born.”

Here are some more Cases & Cooling reviews from around the web:

Click Here to go to Cases & Cooling   CASES & COOLING