Use anti noise, tackle the whole problem. (Score 1)

No, seriously. Take the Sony noise-cancelling headphone idea and scale it up.

The theory goes...

Take a spare system with Audio I/O, sample the whitenoise, reverse the signal, then spit it back out the speakers placed near the systems or inside the cabinet.

Haven't actually seen anything like this done in practice thou it makes tons of sense. Fans and disk drives are a constant source of white noise and hence an "anti sample" could be continously spit out and adjusted infrequently...