It keeps the i7 3770K very cool without resorting to water plumbing. Only drawback is some cases will not enclose it due to its girth.
It runs about 21-28 degrees celsius at idle. At full tilt, I have not seen it go over 60 degrees. For most use, it hovers around the mid thirties.
Here it is running 94-96% CPU load across all cores running a BluRay Handbrake to 1080p h.264 file and creating a 10GB 256 bit AES encrypted Truecrypt file container at the same time. Both are very CPU intensive. 96% load and it never went over 60 degrees.