Summary: Needed an 80mm for cooling off the back of my socket/VRM area that would also fit without mashing up against the back panel. This fit the bill and keeps my socket temps in line with my CPU core.
Pros: Mounts to the back of my CPU socket and is thin enough for a good air gap between the fan and the panel.
Cons: Sleeve bearing, no sheath on the power cord.
Summary: I wanted this to go on the right side panel of a cm690 II. It fits well there. It is specifically recommended for this application so a longer cable would have been nice to give me a bit more flexibility in where I can plug it in on the motherboard.
Pros: - Fits great where I needed it to - Moves a fair bit of air even at lower rpms
Cons: - Pretty loud especially if you let it run at full speed - Would be nice to have a longer cable
Summary: Cooler Master has improved their quality over the years. I used these to replace old Cooler Masters that were 25mm in the front of a 2004 case that is a server now. The thinner 15mm make room for a cushion of air between the fans and my hard drives.
Pros: 15mm thick, good plastic, super quiet. I mean, so quiet that you have to be in a room with no ambient noise at all to MAYBE hear it. Also, the airflow is decent.
Cons: None. Buy these if you need 80mm with no LED's.