I simply use $60 MSI mATX h61-p21 boards. I have two of them and each runs 4x5870s. If you're going to use 4x7970s I may consider putting them on risers with Molex plugs.
This is what im looking for! thanks man, cheap and runs the cards
I bought one new and one open box. I figured if either failed I could send it in as the new one. It saved about $20, but at this point they've been solid. With 4x7970s I would definitely put the cards on Molex risers though. I think I have to be pushing the boundaries of these little boards to supply power to 4x5870s.