I just came over an idea. What if I order a Corsair 750W power supply that carries two 8-pin PCIe connectors (where a 6-pin cable can be connected). I then proceed to order two GeForce 9800 GX2 cards and put them in a Mac Pro. I then hook up the Corsair power supply to the two cards (notice I will have the side door removed for this set-up), as well as a U-shaped paper clip (as according to Corsair's own "how to test your power supply manual) to make the 24-pin ATX cable provide power, thus powering up the power supply and delivering power to the two cards. This way you can have two GeForce 9800 GX2 cards in your Mac Pro, or at least so I believe. Before I go ahead and zap my Mac Pro, purchase two 9800 GX2's I can't use, or somehow reverse the electricity and blow up my house, does anyone have any more information regarding this? Two heads (or 20 for that matter) can think more than one, and probably spot something I didn't think of.