What Works:

Motherboard: MSI-790FX-GD70
Power Supply Brand & Model: OCZ ZX 1250 Watt modular Power Supply
Number & Model GPUs: four 5850s... now 3 5850 + 1 5970
Extender Cables w/Molex Power?: none, but you can do them since 4x 5850 runs really hot and if you OC prepare to have brunt out fans in a few months, on 70+% speed for 24/7. I added spacers inbetween the card ends to get air in. I suggest a spot fan or a extra fan blowing on these also, drops temps 10-15 degrees.