What he said.With 2 680's on 1 1080p monitor you should never be dipping below 60FPS. Even with vsync on.I use Afterburners frame limiter because I don't like vsync, so I always have vsync off. I've never used it with vsync so I'm not sure how they jive together.It all depends on what you would rather have, input lag or frame tearing. Limiting the frame rate to 62FPS takes care of the tearing quite well.
3/24/12 at 9:23pm