where do they sell power supplies like that? Is it dell? did it come with that board also? 
Yes it is a Dell server PSU 750w here is who makes and sales the boards. There was a group buy going on for them I just bought mine direct. You can get the board or the whole setup.
http://www.gekkoscience.com/products/D750_supply_breakout_board.html
They are loud. Awesome PSU's, just loud as hell. GF won't let me have them in the house anymore. Something about "I can't hear myself think over those damn things!!" Thinking isn't her best attribute.
Actually that board has a knob for fan speed so you can turn down and it is really quite.
Yeah, but if you turn them down too much you will start seeing your hash rate drop. I have 3 of them load balanced running 5 OC'd S1's in my warehouse at work.