Maybe this will work for ya...
Dell Dimension 3000: noisy, but fixable
by dlevasseur,Jan 25 '05
Pros: Very cost-effective PC, pre-configured for most common needs.
Cons: Noisy fan and cooling system (see above for fix)
We bought the Dell Dimension 3000 for my wife since her P2-266 had seen its day. Setup was easy, no major hiccups. The only thing that really bugged me (but not my wife) was the cooling system noise. I found if I tipped the PC off vertical even a little the noise would abate. Finally, after putting up with it for a week I took it apart and noted that the fan cowling isn't securely mounted to anything, just sort of snapped into place creating an obvious source for mechanical noise. I'm not proud of the fix, but by rolling up a paper towel and placing it just inside the case's mounting ledge and the fan cowling I was able to reduce the noise to a nearly insignificant level.
I can't upload a picture of the solution here but you can visit my web site, davelevasseur.com you can take a look for yourself. This site doesn't allow direct hyperlinks (understandable policy) so you'll have to copy the above info into your browser yourself. I hope Dell can provide a fix for this in future production.
ASUS Sabertooth 990FX
16 GB Ram
ASUS GeForce 760 GTX
1TB Sata Seagate
100 Gig Maxtor Sata 7200 Rpm
ASUS DRW 24B3S7 ATA Optical
Windows 7 Home Premium
Dell E228WFP 22"