Well Gigabyte proved it's possible on PC, (although I don't really know how impossible it was.) Only thing is it's on PCI Express. But it's just a matter of time before PCI Express comes to Mac anyway. I was wondering what the odd's were of seeing dual 6600 GT's in an iMac G5 were once it goes PCI-E as well as PowerMac G5's. This would certainly solve a great many Mac "gaming gripes", without denting someones wallet too much, as these chips are supposed to be far cheaper than 6800 Ultras even in dual, and give about the same performance apparently.