At the moment its running from 5 volt and its quite noisey, I think i can get it to run slower without to much problem, after giving up the seats the joypad ports were sat in i was quite amazed at how much room there is there and would bet you could get a much bigger fan there instead but with a bit of extra cutting.
This Xbox normaly sits on it's side so i guess joypad 3 & 4 are at the bottom now
oh yeah, nearly forgot, this fan is blowing not sucking, but it keeps the case temp down loads that way, the stock one by the cpu on mine is blowing at like 45 onto the heatsink so drawing through the rear a bit.