Summary: I bought two of these to mount on some hot swap bays that have optional mounting points for a 40 mm fan. The first issue I noticed was that the 2 prong connector on this was considerably larger than the one for the hot swap bay. The pins are almost the same size, but i had to actually cut some of the surrounding plastic from the bay receptacle, to enable this connector to fit. Annoying, but not a big deal.
Summary: I had a bit higher expectations from this fan, but at the end it doesn't has CFM for any serious cooling. But since it is very, very quet (I couldn't hear it), I used couple of splitters and added couple of these fans to blow the air out of the chassis, improving my airflow. So, they cannot be used for serious cooling, but they can help out if placed or right spots.
Summary: I used this fan to replace a stock Intel Northbridge cooling fan. The difference is night and day! While the stock Intel fan sounds like the whine of a jet engine prepping to take off, this Scythe is so whisper quiet that you can't hear it at all. I now have a near-perfect media-center pc. Highly recommended.
Summary: Bought this for a dvr, and even though it pushes a good amount of air for it's size, it is pretty loud. You just have to decide with these tiny fans, do you want performance or quiet. In regards to 40mm fans in general, I have found the Noctua to be the best compromise between noise/performance, but they are also expensive.
Summary: I shut down my media box (AM3+) when not in use because of fan noise. I installed this and now I don't hear it at all. It lets me switch over and watch my Amazon Prime shows and downloads without going through the booting process. Temperature seems fine.
Summary: This fan arrived quickly as promised. It is advertised as a "silent" fan, so I bought it to replace a noisy fan in a security DVR. Not only is the fan not silent, it is noisier than the fan I am trying to replace. Even worse, it moves less air than the fan I want to replace. In addition the mounting screws packaged with the fan are too small for the holes in the fan, so the screws are useless for mounting the fan.
Summary: I chose it because of the positive feedback about being quiet and sturdy. Installed it on my mobo's chipset heatsink - to replace a failed unit. Plugged right in, came with extra adapters (didn't need them - but thoughtful). The jury is still out on the lifespan, but it's what I was looking for.