I'm pulling my hair out here, and have tried everything I can think of.
I have two identical GTX 680s which have been working perfectly in SLI for the last few years. Noticed today my SLI wasn't activated, assumed I just forgot to toggle it back after the most recent driver update, but going to switch it on in the NVidia Control Panel it didn't show as an option.
After reinstalling both the latest (358.50) and previous (355.98) versions of the drivers, including a complete uninstall/reinstall of the drivers, removing and reseating my cards, swapping out my SLI Bridge for one never removed from it's plastic, and then finally resorting to a clean install of the OS I've narrowed down the issue, I just can't make any sense of it.
SLI shows up fine in the NVidia Control Panel after installing a driver, activates, and based on frame rate is working. However once I restart it no longer appears. If it wasn't active before the restart all other options still show, it just leaves out the SLI option as if I only had a single card installed, but both cards are still availible for dedicating to PhysX. If it was active before rebooting the Nvidia Panel only shows the 3D options, nothing else.
Looking in GPU-Z/testing in game, if SLI was activated before a restart, it still seems to be active after, NVidia's control panel just isn't offering it (and seemingly breaking and not offering anything if it is active even though it doesn't think its possible).
Any sugestions of what I could do to try to fix this/narrow the issue? Anything I can do to work out which card it is, or if it's the Mobo, if I'm seeing the early stages of a hardware failure? Anything it could be software wise (after a clean install I doubt it, but can always hope)?
Thanks!
Extra Details:
OS: Windows 10 Pro 64 Bit,
CPU: i7-3770k
GPUs: 2x GTX 680 2GB