I'm not sure what the RPM and CFM of the rear fan that comes with the case is... but is it possible to tell from my build whether the Scythe fan is sufficient? I basically want the most quiet fan, but still want to have enough cooling for my system. The computer will be in sleep mode about 17 hours/day. It will be used about 7 hours/day: 4 hours surfing internet/watching anime, 3 hours playing Diablo 3 on medium settings, which has these system requirements:
Recommended System Specifications
OS: Windows Vista/Windows 7 (Latest Service Packs)
Processor: Intel Core 2 Duo 2.4 GHz or AMD AthlonTM 64 X2 5600+ 2.8 GHz
Memory: 2 GB RAM
Video: NVIDIA GeForce 260 or ATI Radeon HD 4870 or better
I would suggest either a ball bearing or fluid dynamic bearing fan as they are quieter. I've used sleeve bearing fans - CM Sickle Flow (the R4's you're looking at) - and they are mostly really great as far as CFM and noise goes, but I often hear a "tick" sound from the bearing. This happened on 2 of the fans. I still use them, it's not that bad now that the PC is on the floor, but when it was on the desk I could hear it.
FDB fans won't have that issue.
Other than that, most fans under 1400rpm will be nice and quiet. CFM won't matter too much. Scythe S Flex FDB fans are great. So are Gentle Typhoons.
The Arctic Cooling fan you listed looks fine but only if it has speed adjustment built in, or maybe you have a mobo fan pin you could use.
800rpm is probably a little less than you want, although it will work (that Scythe fan)