Is this a gpu or monitor problem?

If I turn my monitor off, or it goes off due to power saving schemes, it will be unable to display GPU powered content instead powering the monitor off entirely every few seconds. Power off entirely not just signal. It I doable all power saving and force Windows to have the PC and display stay on all the time, it doesn’t have this problem.

Might be a Windows problem. My workstation at work had the same thing. IT’s solution was just to disable all power saving.

If I restart Windows functionality is restored

Does your monitor have DP/HDMI Deep Sleep enabled? Sometimes that can cause issues with screens waking back up properly.

I guess you could also try test the culprit by removing the GPU and seeing if it happens on CPU integrated graphics, if you have that.

No integrated to try with.

I never knew about deep sleep—it does indeed have this function so I will have to check the OSD.

Yes, my Asus monitor had this issue, and it was baffling. And annoying.

That seems to have worked! After 1.5 years of leaving monitor on 24/7.