Question Video card seems to be having issues with certain types of lighting and textures in games / videos

Also in settings try setting preferred refresh rate to Highest Available. You can try using a different dispaly port out the back of your gpu see if that changes anything. Sure cables go bad all the time, mostly Hdmi in my experience but it could be the display port cable. But since you get the problem in games and videos I would check the cable. Cheapest thing to start with.