I would try several things......
First try a different screen resolution mode. The current setting may not be right for the monitor.
Then I'd set the color depth to 16m instead of the customary 32m.
Less color resolution lets the screen refresh quicker.
I'd also check to see if there are newer video drivers than what are currently installed.
In one case, on my own PC, where the video was going nutzo, I took the video card out and
washed the video ram, with Denatured Alcohol and an old tooth brush. After drying, I put that
video card back in and it's been running flawlessly ever since. That was over five years ago.
There's an answer,,,,,, you just need to keep looking till you find it.
Good Luck,
Shadow