I have been troubleshooting my Mac Pro (Late 2013) and need some advice. I am having issues with a driver or software related issue I believe. I can start the Mac in SAFE mode and cannot replicate the issue. When starting the Mac Pro, sometimes the system will boot up (and sometimes boot up twice) and go to a screen that flickers different colors or just a black screen with a little light faintly at the bottom of the screen. If the computer goes to sleep or I manually put it in sleep mode, when I try to resume, the screen does the same thing. I've tried everything from disabling startup items that might have been causing the issue, ran disk utilities, to unplugging all USB and Thunderbolt connections, with exception of my Thunderbolt displays, tried different ports, and have even reinstalled macOS Sierra (not a clean install) and the issue still continues. At some point it seems like a hardware issue, but when I boot in SAFE mode it is fine, I have reset the PRAM also. What ideas can anyone offer based on the behavior of this issue? It's like maybe a graphics driver needs to be reinstalled, but I don't know how or where to do this -- and not sure this is the issue.