The EKL Peter with two Noiseblocker BlackSilentPro fans offers both excellent cooling and quiet operation. Then again, five slots are a lot of space to give up, and $140 isn’t exactly cheap. If you do have the room in your case to sacrifice, however, this could end up being a viable approach to quelling the reference design's questionable acoustics.
One major disappointment is the EKL Peter’s manual. It barely deserves to be called helpful. Taking on the seemingly major task of replacing a GPU's heat sink and fan would be much easier if the company provided more information (and made sure that guidance was accurate). The way it stands right now, even a seasoned enthusiast could wind up in trouble.
Its manual wasn't the only issue we had with EKL's Peter. Given the heat sink's price tag, not all of the bundled hardware is of suitable quality. For example, it's way too easy to strip the threads from some of the screws. Fortunately, if you know about this ahead of time you can be extra careful and avoid a more serious problem. We'd also like to think that the cooler's excellent overall performance helps make up for EKL's handful of oversights.
We don't recommend the EKL Peter to anyone queasy about dismantling expensive equipment. The process can be quite unnerving. But if you have a bit of experience taking things apart and putting them back together, are comfortable with the caveats we presented, and have five expansion slots you're willing to sacrifice, it'd be really difficult to beat this heat sink and fan combination with any other air-cooled solution. Once the EKL Peter is installed (set up either for great cooling performance or quiet operation), it’s a joy to have!