SLI is something you cant have on your motherboard... Using a motherboard with 2 PCIEx16 slots you can get 2 graphics cards and run them as 1 therfore doubling the performance... using this you can get some amazing graphical results. but like i say your motherboard doesnt support it... if your looking for a new graphics card just keep looking around and stick to nvidia since you have an nvidia chipset... just compare them like i told you... the more memory and core MHz the better the card is if you want some spectacular graphics have a look at the 7 series graphics cards
