I currently have a BFG GeForce 7900 GSOC 256 mb video card running on a Gigabyte GA-P35-DQ6 775 motherboard (one pcie x16 slot, one pcie x4 slot). I would like to add a 2nd dual dvi video card so I can run 4 monitors. Do I need an identical video card, one that has the same chipset, or can I totally mix and match? I am not a gamer so I don't need the absolute best performance but I would like one with OK performance.