Check what's making the most noise.
I also have a magma (slighly newer rev I think, it's got the thin cable) and I found out the noisiest bit was actually the powersupply. The fans themselves were relatively quiet, and if you're only running dsp cards, you might get away with disconnecting the front fans.
I end up getting a really quiet powersupply (can't remember the make, but it was 400w..might have been a silenx) and that made a huge difference. I also disconnected one of the front fans....so far it has been working fine.
Before that my magma sounded as if it was about to take off!