Hi all. Long time reader, first post.
So here's my HTPC (XBMC)/file server:
case: Antec VSK-2000 (3 120mm fans)
mb: msi s939 neo4 platinum
cpu: x2 2400+ @ 2.64 GHz
ram: 2GB ddr400
heatsink: xigmatek Gaia (120mm fan)
hdds: 6 5400 rpm storage drives, 1 7200 rpm os drive
gpu: sparkle gts 450 1gb fanless
odd: samsung sh-b123 bluray
psu: cooler master silent pro 600w
Needless to say, I wanted to make this rig quieter so I replaced the 3 120mm fans with 2 800 RPM slipstreams and a 1200 RPM slipstream for the exhaust. I replaced the xigmatek 120mm fan with another 1200 RPM slipstream and removed the 40mm fan on the nforce4 chipset and replaced it with a passive zalman heatsink and positioned a 120mm 800 RPM slipstream to blow on the northbridge (gets really hot without it). After doing all this, obviously it was quieter, but I could still hear it. The case has thin side panels, fan grills, and hard feet so I figured I'd adress these things. I wanted to add dampening mass loaded vinyl panels to the side panels, bottom, and top of the case. I also wanted to surround the drives on two sides with acoustic foam and place foam everywhere else it could.
So now the point of this thread. I needed to find the dampening material, acoustic foam, and soft case feet, but didn't want to pay a fortune. So I went looking and ended up at McMaster (if you don't know what McMaster.com is, it is an industrial supply company that basically has everything you could imagine that has to do with engineering at really good prices). At McMaster I found these products:
Sound and Vibration Damping Sheet EVA Mastic DLF=0.1, .079" Thick, 32" X 54" - 9709T39 - $16.62 -http://www.mcmaster.com/#9709t39/=ccwipk
Acoustical Polyurethane Foam Absorber Adhesive Back NRC=0.75, Skinned, 1" Thick, 12 x 54" - 5692T49 - $13.21 http://www.mcmaster.com/#5692t49/=ccwj86
Acoustical Polyurethane Foam Absorber Adhesive Back NRC=0.35, Skinned, 1/2" Thick, 12 x 54" - 5692T61 - $9.04 http://www.mcmaster.com/#5692t61/=ccwkci
Adhesive-Back Load-Rated Polyurethane Bumper 1-1/4" Dia, 5/8" Height, 5-10# Max Load - 8215K6 - $2.84 each http://www.mcmaster.com/#catalog/117/3733/=ccwkwv
Total including shipping was $70.21 and there is enough material here to sound proof at least 2 full sized ATX cases. I used these material with great results. The dampening sheets are easy to cut, have an adhesive back, weigh quite a bit, and work great; case now has a dead thump when you tap it. The foam has a nice adhesive back and is flexible and easy to cut. Absorbs high frequency sounds pretty well. The polyurethane feet are super soft and do a great job isolating the case from my hardwood floor. I recommend getting the medium-soft ones; I got the soft ones and they are really soft. End result is a much quieter computer that you can barely hear. The only noise it makes is the gentle sound of air moving (there are 6 slow moving fans in it), the faint sound of a drive spinning up, and the motor noise of the bluray drive. Overall very happy with the products I selected and the final result.
If you are looking for acoustic foam and dampening material, I recommend checking out McMaster for some great products, good prices, and fast shipping.
I'm on vacation now but I will take pictures of the system when I get back next week!