G-Sync is useful for all GPUs, and regardless of whether you reach 60FPS or not. 60Hz vsync has quite a bit of input lag. You can reduce it with various methods, but it will never be as low as g-sync (which has the same input lag as vsync OFF.) Also, when using 144Hz+ displays, G-Sync is immensely useful. However. the majority of competitive players do not use g-sync. They just run vsync off, g-sync off. So actually g-sync is NOT for competitive players. It's for normal PC gamers.