The Hanns-G is an LCD, I'm assuming. Your refresh rate should always be set to 60Hz, as that is the native refresh rate of the monitor. You will also enjoy a better picture using a DVI/HDMI/DisplayPort connection instead of 15-pin VGA, and using the native resolution (likely 1920x1200 from a Google search). I can't conceive of a way to hurt an LCD by sending it bad video.
The flickering/"tracking" you describe ambiguously, more information about what you are seeing (and what miner software you are using) would help diagnose your issues. Likely the GPUs are running at too high of an aggression. You may be using full-time miner settings on a computer where you really want unintrusive background mining, not leaving enough GPU power to do normal windows things like redraw programs on the screen.