Samsung Monitor Flashes Black and Analog Shows in The Right Corner

[Ninjasty]

Hello , I am having problem
Problem starts randomly or when I start playing games . Monitor start turning black and analog shows in the right corner . And it drives me nuts because I'm very computer illiterate , plz help

 

[Ninjasty]

Update
Everything worked fine for like one year until now , when I start pc everything goes fine and after few hours of gaming it begins .
am done help

 

[Cycloid Torus]

Work through the video subsystem, replacing each element with known good. When the problem goes away, the last element you replaced was the broken one.
Monitor, cable, video card.