1. The Nexus D12SL fan seems to be fairly good at anything. SPCR seems to have had good luck with them in terms of longevity and SPRC has lots and lots of experience with them... far more than any single user.
2. You can get that noise if the fans are running at slightly different speeds.
3. "one at 12pm and one at 3pm" what does that mean?
I was using 2 Nexus fans running at the same speed. I think with the design of this fan using it as a pull fan, the blades are extremely close to the heatsink and that is where the sound originates. I tried several different scythe fans and none did this.
I mean using two fans, both in a push configuration. One down towards the base of the case and one towards the back of the case, at the 12 O'clock and 3 O'clock position. Not sure why I said 3pm, lol.
So what would you recommend as a good fan for this heatsink? I just bought a second scythe PWM fan, the same that came with the unit, the SY1225SL12M-P. Is there one that you would recommend over this. I looked at all the scythe fans and this one seemed to have the best CFM to dba ratio. There may not be that much advantage to using two fans, but I'd like to try. I just started folding and would like to keep temps down as much as possible.
I have only been using Scythe fans for a short time, but I've had a very good experience with them. I also like the Noctuas, but they are often $25 per fan.