I have 2 PCIe video cards, both 8800GTs models but made by different manafacturers and both with different memory/core speeds. The 2 cards in question are: XFX 8800GTS model# PV-T80G-GHD9 and the second an MSI 8800GTS model# NX8800GTS. Question is can I use these 2 cards in SLI config or do the 2 cards need to be identical (as far as GPU version and memory and core speeds are concerned)?