Flickering rectangles on 27-inch Apple Cinema Display

[EvilEvil]

Occasionally rectangles of various colors or static snow flicker on my 27-inch Apple Cinema Display. They go away if I move a window on top of them. Then it doesn't happen for a while. It's hooked up to 2012 Mac mini. I tried running a ram test with Tech Tool and everything seems fine. Is the monitor going bad or is the Mac mini's logic board? Anyone ever encounter this problem?

 

[jettie1767]

My iMac did that two days ago. Brought it in to Apple today and they think it's the video card going bad.

 

[h9826790]

99% that's the graphic card, but not the monitor's problem.