Well, I tried it. The 8800 will not fit in the bottom pci-e x8 slot. The right hand side of the card hits the DVD ata plug and won't quite seat into the slot. So I removed the 470, reinstalled the 8800 on top as the primary card, that and an existing 7600GTOC in the pci-e x16 slot below it.
I'll request an RMA on Monday. So will be looking for another card. How about the GTX285? Does it heat up and run full tilt when you attach a second monitor like the 470 does?