Well, this was from a few months back, but you might find this Article to be of help. Keep in mind that mucking about inside and modifying your case and fans will almost definetly void your warranty. Check and see if the noise is coming from the fans, or the vibrations of the case agianst your worksurface. If it is vibration noise putting a pair of Auralex Mopads underneath will help greatly. If it is just a noisy fan, there's not much you can do to quiet the machine without changing the internals.
You can look into putting the machine into an isolation box or glass-doored enclosure of some sort. In studio situations something like an isorack from Raxxess works well but isn't exactly designed for the home user.
I'm the wrong one to ask about this, I just ripped a huge cooling fan out of a dismantled mainframe here beside my desk at work and attached it to the top of my AKAI DR-8. As soon as the thing comes on it sounds like a 747, but I'm in a sealed control room and the sound doesn't get out into the main body of the studio.
Sounds like my gaming system. I wired an extra hard drive power connection to my extra fans, which can be controlled by a switch on the faceplate (with indicator LED).
Works great for those intensive 3d gaming sessions.
I'm really kind of suprised that liquid cooled rigs haven't found their way from the lan parties into the studio yet. I personally am still to nervous to put anything that could leak or cause condensation into my pc...maybe that's why.