Hi. I´ve seen similar issues in this forum, but not exactly the same as mine.
If my PC (Shuttle SX48) is on and the screen is ok and I then choose to restart the system, windows (7) then restarts, but the screen goes black and stays black.
I have upgraded the BIOS, taken away all power saving options, installed the latest drivers for the Nvidia GF GT 730 and the monitor Samsung s24d590.
So, when you restart the PC, it just hangs and nothing happens? Any problems when you power on the PC? Are there any performance issues?
Please boot in Safe Mode and check if the restarting problem persists. You have done pretty good job trying to solve the issue. It may be worth it to do a fresh Windows installation. This way we may exclude a software issue as part of the problem. Before reinstalling, make sure you have backed up all important data.