Computer hum, reverbs under desk

[quietquest]

My "desktop" computer (which sits on padding on floor) hums.  I understand the mechnical problem. I've mitigated it somewhat.  Don't want the hassle/risk of exchanging it (yet).  The computer sits under a credenza and between the side of the desk and a small filing cabinet, along with the wall making a perfect little resonant chamber. I have considered rearranging the office, however, that will sub-optimize several other functions.  I tried draping some towels on the surface of the "chamber" that the computer sits in, and it made a BIG difference.  So, I'm wondering what kind of acoustic material I could purchase and attach to those surfaces that would do as well as the towels.  According to my spouse, something white and unabtrusive is a requirement.  

Any suggestions would be appreciated.  

Thanks!

[supersoundproofing]

The correct product would be our foam mat. however it only comes in black. you could cover it.

[quietquest]

Thanks.  Would it maintain it's effectiveness if I covered it with cloth, say a light muslin?

[quietquest]

Or how about covering it with contact paper (doesn't seem like that would work so well)...

[Randy S]

those materials will not even come close to the reduction from our foam mat .

[quietquest]

My apologies; I wasn't being clear.  I'm thinking about cosmetic covering for your acoustic foam.  Will contact paper (easiest) or muslin (possible, but tricker) affect the performance of the acoustic foam?

Also, since thicker is more expensive, is there any way to estimate what thickness of the foam is enough?

And, I had eye's on the foam before, (not the "cone" type, just the the flat stuff), but now I can't locate in on your site.  Any pointers on where to find it would be appreciated.

Thanks!

[Randy S]

Yes you can cover it and not effect the performance...it is a closed cell foam.
1/4" should be fine for computers
Here is the link.
http://shop3.mailordercentral.com/supersoundproofing/products.asp?dept=17