A 747 on your desk is fine if you don't want to get any work done, but for the rest of us there's almost nothing more valuable than a quite workhorse.

As for a solution, try and get a replacement, but if that doesn't work get a couple panaflows (really really quite fans) and DIY. PSUs aren't that hard to open up, just don't touch the capacitors - you can get one nasty jolt. If that doesn't appeal to you try lining the case with some sound insulating material. That can probably knock out a few Dbs