A computer can be noisy, most of the average desktops are not that far from a vacuum cleaner sitting on your desk. The main reason for the noise are the fans to get away all the heat generated. As Trubadour demonstrated this heat is enough to fry an egg (I found this first through Sahil). When you take a closer look the pictures you can see that machine is water cooled. At first thought this PC would be abolutely silent, having no fan. But the pump needed to pump the water around makes some noise as well, having had loads of aquaria I know that can be pretty bad, especially when the valves start leaking. Fritz Onion went back to (silent) fans having found suspicious green moist in his machine. I silenced my Hoover by replacing power supply, CPU fan and graphics fan. A hell of a difference.
But still I am not content. Now the PC’s noise melts away in the background I start hearing new things. The electronics in a flat panel can emit quite a lot of irritating noises. Afaik they contain high frequency oscilators which vibrate. Very irritating. Classic CRT’s, especially TV’s, can be bad as well. The cathode ray tube emits a tone which the audio cannot mask. So what’s next in tweaking land ? Silent fans do work and are great fun to install, I’ll be the first one to try an HF silencer. Don’t know yet what they’ll look like.
But it is an arms race lost in advance. Switch off your PC and you will hear squeeking lightbulbs and hissing heating pipes. I wish I could play some music while working. To me it’s one or the other. As its looking now I’ll end up in a monastry where the only disturbing sound will be my pen scratching the perkament. With integerated digitizer :)