I have just installed windows 10 on my MacPro 5,1 without bootcamp and installed Bootcamp drivers via WindowSupport. I have had this issue since ive installed the OS. I believe it has something to do with the the drivers given by nVidia as when i boot into windows using safe boot with networking, this issue does not occur.However i am using a triple screen setup which might be the cause and when booted with safe mode only one screen is being used. Ive tried removing the nVidia drivers and clean installing it. Ive tried using the original rom and it works properly but that wont be much of a viable option as i need to bootscreen from my GTX 680 in order to boot into windows and do further troubleshooting in the future. Ive tried using older drivers from nVidia still the same problem and i have tried disabling fast boot in the control panel. The black screen only appears right after the spinning windows boot screen and only stays for a few minutes before bring me to the login screen.Any help will be appreciated.