So there is only one way to truly silence your studio: put everything with moving parts in a separate room and run a bunch of cables under the door. Sadly, this is not practical for most of us. A couple apartments ago, I actually had a setup like this, with my computer sitting in a hallway on the other side of a closed door. It was blissfully quiet, but quite hazardous to cross the mess of cables when entering the room. Since then I have not had the luxury of putting my gear in a room where I could close the door.
At any rate, if you don’t have another room to put your computer in, the next best thing is to make it quieter. You can actually spend a ton of cash making your PC dead silent, but I recently got most of the way there for well under a hundred bucks. The worst culprits are the things the move the most: the power supply (with its built-in cooling fan) and the CPU cooling fan. Here’s what I got.
Nexus NX-3000 Real Silent PSU: Well, “Real Silent” is a straight-up lie. It’s very quiet, but 19 db(A) is not silent last I checked. I still recommend it. Some people might suggest that you need more than 300W from your PSU, but I don’t know if that applies to musical setups. I run about a million USB-powered devices with no trouble.
Zalman CNPS9500 CPU fan: This is quite a monstrosity; the photos on the web site don’t really show how big it is. Basically, the main way to make a quieter CPU cooler is to make the fan bigger and slower. But of course a big slow fan doesn’t cool as well, so you need a bigger heat sink with lots of surface area to compensate. This fan supports dynamic speed controls; in other words, the fan spins slowly at start and only increases in speed as needed.
In general, End PC Noise has a good selection of quiet computer parts. I noticed that most web sites about customizing your PC are geared toward people who play video games, but musicians stand to gain just as much.