The guys over at The Modfathers take a look at Xoxide's 6-Port Baybus:
Everyone has at least a few fans in their case as its the primary method of cooling for a computer; even watercoolers will have one or two. These fans, especially more powerful ones, can cause quite a bit of noise. Since most of us want to remain sane while in the presence of their computer, people look for ways to quieten their fans. Some simply buy quiet fans, like panaflos, however why compromise? you can run those powerful fans at a quieter state by lowering the voltage applied to them, and typically without losing much performance.. A baybus allows you to change the voltage applied to a fan easily, suddenly making fan and noise control simple. Several companies produce baybus's, and I will be taking a look at Xoxide's 6-Port Blue/Red Baybus.