I had one of my 980tis flash by MVC (love having a boot screen, thanks MVC!) but at the samd time I got a second 980ti that I wanted to SLI in Windows. I don't get the option in the Nvidia control panel to enable SLI. Just unistalled and reinstalled the nvidia drivers, but still no option. Running a Mac Pro 4,1 (flashed as 5,1) and Windows 10 64bit. Anyone else running SLI in Windows with one flashed card and one stock?