greens :
He has two full size PCIE x16 slots.
I do believe that a 8800 GTX 512mb will run just fine on a x4 slot, it isn't like its going to saturate the x8.
There is no explicit requirement that SLI must use 2 x8 slots, its just recommended to eliminate bottleneck.
You can SLI two 8800GTS on that board.
Size don't matter, it what it run on. and SLI is license by nvidia, the mobo need to meet the requirement
2 x8, and paid nvidia to have it on the mobo(bios? something?), so they can put it on the spec. I don't see anywhere it said SLI anywhere on gigabyte site for the mobo. Do you?
1 x PCI Express x16 slot, running at x16 (PCIEX16)
* For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16 slot.
1 x PCI Express x16 slot, running at x4 (PCIEX4)
2 x PCI Express x1 slots
(All of the PCI Express slots conform to PCI Express 3.0 standard.)
2 x PCI slots