Dell E2316h bad PSU or main board?

Good day I have a Dell E2316h that starts flickering after a few hours of use for the day. After a few hours the screen starts to flicker and jump. Could it be the mainboad or the PSU? I would like to know so I can order the part and not buy the wrong part. I have uploaded a video of the monitor flicking. The monitor also flickers alot when there is alot of movement on the screen which brings me to believe that it could be the mainboard. I am not sure and I have found both part on the internet but I want to buy the right parts without wasting my money.