Hello, have you checked drivers for graphics yet ? Can you hook up another monitor to check for monitor issues ?

Look in Device Manager, which is located in your Control Panel, which you would see from the Start button, Open up Device manager and update/check Display Adapters.

That kinda makes it seem as if the monitor itself is failing.

Trouble shooting would have you use another known good cable to rule out cable . But, in my humble opinion, it would seem as if the monitor has bad hardware . Check out the cable first, of course.

The most inexpensive way to solve an issue is of course to use known troubleshooting steps . The repair shop uses that method, thing is, they have bins of known good parts and they will swap out til the issue is solved, for the home user, our resources are , for the most part , limited . So, with that in mind, do what you can , before you have no choice but to take it to a Repair Shop. Good luck with this issue .