I could no longer stand the fingers on a chalk board noise of the fans coming from the G4 so I decided to do something about.
I replaced all the fans with Silenx fans (including) the 80mm power supply fan, and the CPU fan (which was the biggest offender) I even cut out the plastic and metal grill that covers power supply fan.
Result?
If it wasn't for the hard drive you would not be able to tell if it was on or not, it is that quiet.
So then I moved on to the 7 slot expansion chassis. This was a lot easier to replace the fans in. The power supply was a lot easier to work on as it has a lot more room in it than the G4 supply. The two front fans I stepped up from 92mm to 100mm.
The result?
It is a lot quieter, I did not cut out the power supply grill which believe it or not really adds to the sound level so I am going to do that on this one as well. The front fans a quieter but suffer still from chassis resonance which amplifies any fan noise, so i am going to put in some dampening.
Will let you know how that works out