I've got 6 80mm YS-Tech fans in my case which drone out the evil whine of the black label fan on my PAL6035 and make a deeper noise which aint so anoying The lower voltage idea is good, but it would probably perform worse than a YS-Tech 60mm, so the best thing is just to bear the noise, or wear some earplugs, as K6-III said.
Well I cheated, i just switched to liquid, and have 2 140mm 24v fans running @7v each, very slow running through rad, enough to keep Tbird 1gig at 30c full load, STEALTH cooling
( except for the huge rad sat outside of case )
-----------> I have a PC, and its got a printer....
I took my 60mm fan off of my Alpha PAL6035 and made a duct to an 80mm 40cfm fan on the back of my case. It moves more air and only spins at 2000 rpm NOT 6800!! Big difference and much quieter. Although it took me a couple hours building the duct out of cardboard and that foil tape. On the Alpha it sucks, but you could make it blow or suck. My T-Bird is at 26c idle and 38c 100% load. Try it and you'll never go back.