Silencing can be an obsession, and obsessions are never pretty. Here is my current rig, what I call the "Experiment Box," or "Big Geek," (after the submersible in the Abyss).
Never ever put sound-deadening material on the outside of your computer... It really doesn't do you a lick of good, and it hardly serves to silence much of anything. Yes, that is an extra floppy drive, a USB Hub, and a big red switch embedded in the front of the machine as if thrown there by some evil giant. The switch was originally going to alternate the hard drives, but it currently doesn't do anything. Perhaps it will be an extra fan controller. The USB hub is pass-through, and plugs in the back of the machine. The model number is there because the manufacturer didn't bother to tag it, which makes keeping track of components a problem.
The Compact Flash drive works wonderfully, but I still can't boot from it into debian, and I'm starting to suspect it isn't possible. The speed holes on the side make the computer go faster. And yes, that is a fan at the bottom right of the image. It is in the perfect place to cool a hard drive that might be lying on the base, no?
Sadly, it is every bit as pretty on the inside as on the outside. If you look very closely in the front you will see a Y molex adapted to give 5v - 7v outs. Most everything is currently 5, but it doesn't hurt to prepare. The 2 sunons in the back are just waiting to be replaced, but they don't produce much noise at 5, so they were a lower priority than replacing the power supply (which added a lot of cabling). The 7v fan is a 60mm Vantec Stealth on the CPU. Once again, panaflo coming... once I can figure out how to mount it. The second fan hole was not fun to cut, but it works. They also blow very close to the CPU, which is fortunate.
Without those rounded cables there would be absolutely no airflow, but with them air can pretty much go where it wants to. This is a mini tower which makes airflow a big issue. There are 3 intake fans, one CPU fan, and the PS output fan. It's a pressure-positive system, which helps avoid dust buildup.
If you look really closely at the bottom-right of the image you can see the Hard Drive enclosure.
Ah my favorite, the HD enclosure. It is made from an old AT Powersupply from "Little Geek," the 486 counterpart to this computer until its untimely death. The old exhaust hole now lines up with the Panaflo intake fan (upper-right of the image) and fits two drives nicely. Air goes in towards the sides (the hot part), and exits out the back onto the network card. The foam was from the shipping foam from the HD. Rubber bands complete the drill, keping any vibrations that reach the enclosure from reaching out to the machine outside. The thermometer is creeping up to 39 degrees Celcius, a very reasonable number especially with the Fan so far away.
That's it, that's my little system. With the new PS, there isn't quite as much to show you all, but I hope you learned something anyway. I'll post more information if I think of it.