I bought one of these 3 days ago, installed it today.
CPU is incredibly cool. 4.3 GHz on a 2550k @ 51C under load.
HOWEVER (and this is a big HOWEVER):
There is an audible squeal from the pump. With a quiet room it sounds like a 6 year old playing one of those plastic flutes they give them in elementary school.
Heatsinks and coolers are the LAST thing I want to have to replace. Sigh. I'm going to give them another shot and see if they will replace this one with a quiet one. You guys will be the first to hear the verdict.