I decided to redo my Windows 10 machine. I never had any issues playing games, or with SLI or anything but my machine was a Windows 8 machine, then upgraded to 8.1, then upgraded to 10 over the years and I always wondered if I should just do a clean install of 10 as I do not trust upgrades. It was basically time to just clean it up.
 
However, since the reinstall of Windows 10 I have had constant issues with SLI. I have a work around, but it's a PITA.
 
The option to enable SLI disappears completely from the NVidia control panel. I only get the surround options.
If I reinstall the latest driver, the option returns, I can enable SLI again, play games etc, all is good until I reboot and sure enough the SLI option is gone again.
I did a driver wipe, complete uninstall, reinstall drivers again all is good until I reboot.
So now, I have found that if I open device manager, disable the 2nd card, then re-enable it, the SLI option returns and I can enable it.  This saves me from reinstalling drivers every other day, but why is this happening? Everything worked fine on my previous Windows 10 install.
 
 
 
 

Is the SLI bridge connected when installing the drivers? I had a similar problem. ALL I did was DDU the nvidia drivers on safemode, installed the GPUs 1 at a time, then once both cards are in add the SLI bridge and reboot. Everything came up perfect, and this is with using 2 diff 970s, a hybrid and a FTW+.

 
I did ddu after windows updates and then reinstall drivers. This was about 2 weeks back now. There's been newer NVidia releases since then.
 
I can't see it being hardware, or bridge - all I did was reinstall windows. The fact that I can get around it by disabling one card for a second seems to indicate some sort of software glitch.
 
 I did not try removing the 2nd card, then wipe drivers in safe mode, then reinstall drivers, then put in second card. I'll give that a shot tonight. That was the only thing left I could think of to try.

So nothing mentioned above helped. I do not have another sli bridge but again, everything was working before I redone windows 10.
 
So anytime I reboot I see this
 

 
if I disable then re-enable one of the cards like this

 
It works again - all the options come back

 
But it says sli is on, most times I have to turn it off, then back on again in order for it actually work in games.
 
 
 
 

will do, thanks. Just worked 20hr shift, I'm a sys admin, I'll try when I wake up in two days lol