sli mobo, 2 video card, same card recommended, enough juice on psu amps doesnt HAVE to be sli certified but it is safer to have one. remember to plug the 4 pin power on the mobo... as least mines has one and is required or it won't work. connect the sli bridge, if it wont fit then you know you plug one card into the wrong pcix slot. you need to reinstall the video drivers.