Ok, this is a more tricky question than the run of the mill "SLI or no?!" So here it is...
Currently, on the market, nVidia has blessed us with the GTX 660 Ti and the GTX 670 with only one major difference between them: 192-bit interface bus vs 256-bit interface bus. My question is simple, and hopefully I can get a straight answer.
If you have a motherboard that is SLI capable (8x8), would that act as a crimp on the actual bus speed? I.e. two 256-bit cards in SLI/CF in 8x8 operation would have their buses in a more limited operation? Therefore, would it give to reason that on this specific setup (SLI/CF 8x8), there would be absolutely no difference between a pair of 256-bit and 192-bit cards paired?
I actually see a lot of benchmarks where 660 Ti in SLI meets the 670 in SLI.
I'm not sure I fully understand what you are asking. As you probably already know, X8 bandwidth with PCIe verson 2.0 (or 3.0) is still faster than the cards can saturate completely. So the card with the wider bus would naturally have the advantage.