Excuse me if you find this hard to understand.
For the past few months my screen has been flickering after about 20 minutes or so of turning the pc on. Then the screen goes to about half the size and the bottom half is black. I don't lose any of the screen in the black half, it just all sort of squashes up into the top half of the screen.
Now it is happening in my games. Instead of the game covering the whole screen it only covers half of the screen. I brought a new graphics card in case it was that (it wasn't)
I have reinstalled latest drivers for the monitor and other things but that didn't help.
I am normally good at fixing things but this has me stumped. Any help will be gratefully appreciated.

Frank.

Try either resetting the monitor's factory settings. Or. Try using a different monitor.