I wanted to get the noise down on (and possibly squeeze a bit more hashes out of) my 60GH single.
I started by replacing the case fans with the Corsair SP 120. Worked just fine, temperature seemed slightly improved, big noise win.
I wanted to go down further on noise, and it seemed the forums were converging on the Noctua fans, so I replaced with CPU fans with Noctua NF-A9x14s. Another big win on the quiet, though thermal performance seems a little degraded (tough to say).
Here's my dilemma -- after I replaced the CPU fans (I'm 90% sure this wasn't happening with just the Corsair's and the stock CPU fans), I noticed air backflow from the intake fan. Running my finger across the surface, it seems like about 30-50% of the area of the fan is expelling air (again: from the intake fan) and the remainder is taking it in.
This seems wrong to me...and might help explain why the thermal isn't performing as I would expect.
My initial suspicions were that the intake fan wasn't generating enough static pressure (as another thread suggested), so I looked at replacing them with the Noctua NF-P12 (again, as that thread had suggested). Thing is: the NF-P12, while quieter, produces less static pressure and less airflow than the corsair. So it seems unlikely that it would help the situation.
Does anybody have any thoughts? Is the air backflow something I should just ignore?