Blurred display

So there's this blurry rectangle in the corner of my screen that just randomly popped up while I was playing a game, I don't know if the game caused it but now it's just there. It covers up just about everything. I have tried unplugging on plugging back in my adapter but that didn't work, I...

So, ill be upgrading to a 1060 soon, and i was just wondering, can i SLI my current graphics card(a 760) and a 1060 just to squeeze a bit more graphical power, or am i better off just selling it?