I've got an oldish PC fan on the front of this at the moment but I'd rather have a decent one as the Stock fan at the back is quite loud. Is there a recommended CFM to use with these?
Temps are 42C at the moment, is this normal?
I use Artic F12 PWM fans. One on each end both blowing in. Make sure it can breath freely from the bottom, e.g. a wire shelf or little block in the 4 corners.
42C sounds good but it really depends on the ambient temperature as to how cool you can run. At this moment mine are ranging from 38 (out in the cold garage) to 51 (inside in between 2 others).