Question Strange issue with my monitor, possibly the graphics card ?

Aug 28, 2021
Graphics Card : Nvidia Geforce GTX 960
Monitor: Dell S2409w, second monitor is an old Gateway.

Problem: Start PC up, monitor comes up no issues. Can play games and anything else I need to for as long as I want. I normally leave my PC on all the time, turn off monitors at night. Starting a few weeks ago, when I turn off the Dell, when I go to turn on, it lights up but with a black screen. Monitor is on, can move mouse over to it but nothing is visible so can't interact.

Gateway has no issues. Easy fix is to do a restart of PC, with this monitor comes up with no problem, once again works fine until I shut it down. Now, recently If I Alt+Tab out of a full screen game it goes black and I am unable to access anything on it. Not similar to turning off as that would make the Gateway primary screen and can do anything, but once the Dell comes back online double monitor settings take hold and screen is still black. Have tried reinstalling drivers, updating Graphics card drivers no change.

Any Ideas would be appreciated.