why not bring out the motherboard manual or drop the vendor a support email? Technically; the GTX is capable of doing Tri-SLI; I would assume, logically, it's possible to put any two cards in any two slots combination. Look in the bios to see if there is switch. For my nForce4 Asus motherboard; I could actually use the 2nd PCIE-16 for video card (single and none SLI); all I had to do is change the bios to say my card is in the 2nd slot. But Asus recommend to have the card in the first slot if not SLI; but it's there for your option.