As described the system is a GA-Z77-D3H (rev 1 I assume as I see no revision on the mobo) with an I5 3570k CPU. I have 2 x NVIDIA GTX 560 ti's, which I'm attempting to get working with Windows 7 x64 and the latest NVIDIA drivers. For some reason, although both cards are recognised, and work with multiple monitors, SLI is not available. Now I'm fairly sure, during a test install of Windows 8, before reverting back to Windows 7 x64, that I had this working in that I'm sure I saw the SLI options in the display manager!
Anyhow, I don't own a copy of windows 8, so I'm using good old Windows 7.
Looking closely I believe this issue is related to the bus speeds for the only 2 channels available for my cards, that is the 2 blue slots listed as x4 and x16. I hear that the max I can get is both these cards running at x8 bus speeds because of shared resources. Great! however, the GPU-Z channel reports that 1 is running at x4 and the other at x16. I've checked all the settings I can think of playing with in the BIOS, resetting to defaults, all sorts. However, I cannot seem to get the bus speed of 1 to display in CPU-Z as x8 for both. I believe this is the cause of my SLI issues as running cards at 2 different speeds will not allow for SLI. These cards are identical, same design/bios version and all!
I've tried swapping the SLI cable, but no luck!
Anyone have any ideas? I've spent hours and hours searching the web looking for a solution.
