How Does G-SYNC Work
Now that we’ve explained what happens when V-Sync is enabled or disabled, understanding what NVIDIA’s G-SYNC technology does should be simple. The image below illustrates how frames are output to a G-SYNC equipped screen, when G-SYNC is enabled in NVIDIA’s drivers.
As you can see, when a frame is complete, it is scanned out to the screen. Frame 1 finishes is X amount of time, and it’s sent to the display. Frame 2 takes a bit longer, but when it is done, it is sent out to the screen, and so on. G-SYNC removes the fixed refresh rate limitation of today’s screens and transfers the timing to the GPU. The screen’s refresh rate is dynamically adjusted to stay in-sync with the GPU, regardless of the frame rate, though G-SYNC is limited to refresh rates between 30 and 144Hz. In doing so, G-SYNC eliminates the screen tearing associated with disabling V-Sync, and eliminates the lag and stutter that come when V-Sync is enabled.
NVIDIA achieved this feat by developing the G-SYNC module, which will be featured in a number of new monitors starting next year. The G-SYNC module replaces the scaler and controller boards in current displays and allows for the dynamic refresh rates mentioned earlier.
The module is comprised of an FPGA—programmed by NVIDIA—a bit of DRAM, and a DisplayPort input. At this time, G-SYNC requires a Kepler-based GPU, with a DP output, and obviously a G-SYNC enabled display. To fully appreciate the technology, a high-DPI gaming mouse is also recommended.