I will never buy Scythe fans again. They still make their money off selling cheap fans with terrible sleeve bearings. There's no reason they should be selling sleeve bearings. I bought 5 a while back, and 3 of them were dead in 3 months. The other 2 were on their way out. Bought some Cougar Hydro Dynamic bearing fans, they've been rock solid for 18 months now, and they're quieter!
Depends on the fan. The GT 1850RPM's are excellent, with ball bearings and below average noise levels considering the air they put out.Those other fans are my leftovers from years ago. I tend to like sleeve bearing fans in my main PC because I'm a silence freak, and sleeve bearings have virtually no motor noise at low RPM's, whereas other motor types tend to have a tiny bit, enough for me to avoid them. But for a 24/7 mining rig and the higher temps that come with it, I understand the value of using good quality fans, hence the Scythe GT's.
