H50?
I built my last PC with one... ended up not liking it and switched back to air (Megahalems). The fan wasn't so much the problem as it was the pump... the pump introduced a low level, but pervasive hum to the normal woosh of the fans I was accustomed to. The overclocks aren't significantly better with the H50 as compared to the better air coolers out there either, so I felt the addition pump noise wasn't worth it. I've built my water loops before, so I knew the pump was going to add an amount of noise... but I guess when I spent $60-70 on the H50, it seemed like spending $60-70 on an air cooler with no added pump noise and comparable temperatures seemed like a better choice to me.
It's a really easy install though, I was really impressed by the installation... wouldn't have been able to tell that this was Corsair's first venture into CPU cooling (even though it's a re-branded kit...), you can tell they did some research. Corsair in general has really been impressing me with some of their more recent offerings, like the 800D and 700D cases.