Wait for Vertical Sync: Vertical Sync (Vertical Synchronization, also called VSync) is the synchronization of your graphics card and monitor's abilities to redraw the screen a number of times each second (measured in FPS or Hz). If this slider is set to 'Application Preference', whether VSync is enabled or disabled will depend on the VSync setting in each particular game. This is the mode I strongly recommend, since you can then adjust VSync in each game separately. If you are certain you want to disable VSync for all your games, select 'Always Off' here. Generally speaking, turning off VSync gives the fastest performance however if VSync is disabled you may see some image "tearing" as your monitor and graphics card go slightly out of synchronization when the refresh rate exceeds the monitor's abilities. If you are certain you want to force VSync to be enabled in all your games, regardless of their individual settings, select 'Always On' here (not recommended). When VSync is enabled, this removes all image tearing, but can reduce performance and limits your maximum framerate to the refresh rate (e.g. at 70Hz, with VSync on your maximum FPS in a game can only be 70 frames per second). Note that under OpenGL, 'Application Preference' is actually split into 'Default On' and 'Default Off' - this means that VSync will be On or Off by default unless specified otherwise by the game.