I have recently converted an old FD Define R3 case to a FreeNAS homeserver and stuck it in the cupboard. It is pretty much idling all the time but the cupboard, case and six WD Reds proved a bit more of a challenge than I thought, so I have turned up fan speeds a bit. That of course creates more noise. The fans are all new, and I would prefer not going down the route of buying new ones. I am also doubting whether I would gain more silence doing so.
At 30%-50% duty cycle the noise level is quite fine for a cupboard server, but now during summer I seem to need 70-90% duty cycle at least, and that creates more noise.
So, my thinking is that much of the noise when speeding up the exhaust fans comes from the metal mesh that the air has to pass through. What if I simply cut away the metal mesh so the the fans would pull out air through two open holes instead of meshed openings? I presume the airflow would be improved, but am I likely to remove noise? (Whenever I have tried a fan outside the case they have sounded very "calm swooshing", whereas if I stick them on front of a mesh it seems the pitch goes up several notches.)
- Exhaust : 2 x Scythe Slipstream PWM 120mm
- CPU : BeQuiet Silent Wings 2 PWM 120mm (came with PureRock cooler)
- Intake : 2 x Fractal Design X2 GP-12 120mm, 1200rpm, but due to some hickup in the fan headers of my Supermicro board they run at 2400rpm. (these fans are 3pin and stay at this rpm all the time, but at lower duty cycles they are not a problem, hence I am looking at the exhaust to lower noise at higher duty cycles)