Are both monitors the same make and model? A couple things come to mind as I too use a dual monitor setup. First check your native resolutions on both monitors and make sure they are set to that setting. Second check your refresh rate on both monitors and play with those settings. Right click any where on an open area of the desktop, select screen resolution, check here for your native/recommended res settings. Click advance settings, click monitor tab, then screen refresh rate.....here is where you change those settings.