So it doesn't show as cable unplugged / No signal detected..? Just blacked display..?
Have tried different cable / display port?
Could also try unplugging then connecting the display cable.. My RX 570 when I pushed the OC. a little far or had to restart unexpectedly the display would show no signal until either video cable was unplugged and plugged in again or it reached the WIN login 4K HDR activated..
Not sure if it's trait of the Vid card, Windows or the display.. but forced restarts obviously skipped some signal / step that told the display to drop of of 4K HDR and back to whatever res POST / boot displays in..
Does NUM lock / sound or alike still work when display cuts out? Or is everything frozen / unresponsive?
Try seeing if CAPS still turns on and off when display goes and if so try a blind restart.. if it was idle @ desktop try ALT+F4, down arrow once, then enter.. or "ctrl+alt+del, press TAB 8 times then enter down key twice and enter
And see if it restarts Windows and displays again..
.... Another thought too... If you have a spare drive or large enough USB stick you could unplug your current OS drive and try a test install of Windows on a spare HD or even fair sized USB STICK.. if nothing available with enough GB could even create a Linux boot stick and see if any of the problems still happen.. if yes then most likely not a driver / software issue.
Depending on skill / Windows knowledge you could check any admin logs / error reports for any extra info or hint..
--- Most of these should come up if you search admin tools on the Start Menu ---
Start, type..: reliability mon and should point to reliability monitor..
Start, type - sysinfo expand software environment, then Windows error reporting
Start , type - event viewer and especially look at any critical and error level events that stand out or have recurring entries..
Start - system configuration has options for diagnostic start up, enable basic logging start.. There's also a logged boot option, basic or base..? video boot mode, safe or minimal boot option and individual control of startup service packages. etc.