I'm pretty sure what you're experiencing is known as screen tearing, which can occur on some monitors when the FPS that you're getting is higher than your monitors refresh rate. It's really kind of a hit or miss depending on your monitor, I've never experienced it myself. I think the best solution to this problem would be to either play with VSync on, or look around online to find a monitor that doesn't have the problem and buy it instead. Definitely try VSync first, and if you really feel like it isn't working out for you, then you might have to save up and try a different monitor.