Reducing Fan Noise

[Walker]

Quiet

I can honestly say that the loudest thing in my machine is my 56x CD rom drive.. For a quiet HSF take a look at the zalman options. i got one of tose and it turned my case into a kitten and it lowered my temp...Plus they look really coool....:grinthumb

 

[T-Shirt]

Bigger lower RPM fans (moving the same CFM)
High quality fans (sleeve bearings are quieter)
Mounting isolation- rubber grommets, O-rings, a rubber gasket (neoprene is best)between the fan and case.
Keep it CLEAN a very small amount of dust lower fan effiencentcy alot, aslight imbalance of the dust (like you running a finger over one blade (with the fan OFF!) will cause a lot of vibration.
Use a good Filter,- helps keep it clean and cuts down on "air"
noise