re: Help with the ole PC

That's tearing. It happens when your gpu is producing more images than your monitor can handle. I recommend monitoring your frames so you have an idea when it happens because it usually happens like I said. However there are time I have experienced when it is less frames than that which I don't understand why still.

You can either up your settings which will lower frame rates and possibly find a happy medium or enable vsync. Problem with vsync is it can lower your frames too much. It's a tricky feature.