Loses AC, down for 3 days, intermit Sleep for 2.5s PS or MB?

If this monitor loses AC power…I have to wait 72 hours to try to use it…waiting 3 solid days and the monitor will come up as always, well the always before this quirk showed up:

NOW; it comes up and some time into using it, it goes to sleep but only for a second or two. Maybe 1.5-3.4 what do I know…

Today it was unusable sleep wiggle mouse, awake 3-5 seconds. repeat.

Ive read of replacing this board or that and not seeing folk check solved

Yhe freaky loss of power screams PSU to me and the sleeping kind of behavior whispers main board

Thanks!

Michael

I thought Id come yesterday to add that this is a MacPro 2013 system. I'm straight into the Mac, not a hub. I had thought if there was something to a MDP plugging into a TB2 port, maybe adding a hub might help or IF this monitor should go to a new setting maybe I replace with a Thunderbolt version, the 1407?? This morning as expected the monitor fired up like it was NEW!

Expecting that things ARE what they ARE I will watch for the blinking/sleeping to return and check the display with a flashlight. Shot a pic this morning, should I need to update I'll grab a shot of the screen to see Thank you for reading :). Michael