Greetings,
My machines are not silent but they are nicely quiet. I have two boxes
here with Antec Sonata II cases, fanless video cards, and "smart" Antec
PSUs. You can get cases from Antec B stock at very reasonable prices. My
flat-screen monitors don't make any noise, nor do they interfere with my
audio in any way. Both boxes use Zalman fans for CPU cooling, also very
quiet.
Fans are noisy, and the fans on cheaper video cards are particularly
nasty. Drives are also noisy, but the Antec cases have "soft" drive
mounts that absorb most of the noise.
Btw, the video systems in all my machines are powered by the nVidia
proprietary drivers, because I need accelerated 3D for some of my work.
The audio hardware is identical on the two desktop systems (M-Audio
Delta 66 + preamps).
I keep the machines on the carpeted floor, each on its own piece of 2x4
to further minimize rumble, and I keep my sound system's power amp
(Alesis RA-100) in another room. The RA is quiet enough to keep in the
main room, but I got in the habit of keeping it apart from the other gear.
Make sure that everything in the vicinity of your recording area is
nailed down tight, nothing vibrating or rattling. It's axiomatic: If
something can make noise in the room, it will. Reduce the possibilities. :)
Best,
dp