The Holy Grail in computer graphics and, in particular, games is the suspension of disbelief. If the graphics are good enough the player will become immersed and lose himself in the game (assuming it has a good story).
But you can't reach this level of nirvana if you are distracted by artifacts on the screen caused by the incompatibilities between the timing circuits in the LCD monitor and those in the graphics add-in board (AIB).
Gamers have deep pockets and even deeper passions. And they are legion, numbering from 3 million to 50 million depending upon the intensity and frequency with which they play.
The hard-core gamers, the 3 million to 5 million, buy the best and expect the best, and they complain the loudest when they don't get it. They get listened to. The PC builders hear them, the monitor suppliers hear them, and you can bet the AIB and GPU suppliers hear them.
If you have ever played an AAA action game you have probably experienced the problem -- the image is jerky, it gets "tears" in it, it stutters.
And even if you didn't actually notice those artifacts, you felt them. The game play just wasn't smooth, it just didn't feel right, and as soon as that happens, as subconscious as it may be, you've lost the suspension of disbelief and you're looking at the game rather than being in the game. And when you start looking at a game, instead of being in it, you start to abandon the game.
And sometimes, if you're like some gamers, you'll start bad-mouthing the game. Gamers have incredible influence; they get listened to by their peers and even casual users looking for advice.
Nvidia's heart and soul is in gaming. It makes most of its money selling to, and hopefully satisfying, the gaming community. And when the community says jump, Nvidia asks how high. The company also tries to not ever be asked to jump; it tries to anticipate the needs and frustrations of the gamers. And with that motivation it developed G-Sync.
G-Sync is the product name for a circuit board that Nvidia sells to monitor manufacturers, to replace another circuit board in the monitor known as a scaler board. The scaler board is there to control the monitor and to scale an input frame from whatever resolution the raw input (VGA, DVI, HDMI) is driving up to the native resolution of the panel.
Scalers also manipulate things like color hue, intensity, and contrast, and for traditional displays the scaler works just fine.
However, the fundamental issue that causes stutter and tearing is unaddressed by this older technology. Stated simply, since GPUs render with a variable rate (based on game scene complexity) there is a rate mismatch with a fixed refresh monitor. As an example, imagine a game running at 45 FPS attached to a 60 Hz display: How do GPUs make that work? In our example, 15 frames every second are missing.
Today GPUs use two techniques to bridge this gap: V-Sync On or V-Sync Off, which have significant perception issues. When V-Sync is on, the GPU simply redisplays previously rendered frames whenever the render rate can't keep up with the display. In our example this would lead to a pattern where one in three frames is repeated.
The problem is that when that frame is repeated, apparent motion in the game freezes for a moment, which gamers perceive as a stutter.
The second alternative is to turn off V-Sync, which allows the GPU to start displaying newly rendered frames at any time out of sync with the monitor refresh. This results in a phenomenon called "tearing" where the top part of a refresh shows an old frame and the bottom part of the refresh shows a new frame. Your brain sees that corruption and calls "bull" on the image.
G-Sync fixes all this by simply refreshing the monitor in sync with the render rate of the GPU. Images never tear or stutter since there is no more rate mismatch. By replacing the scaler inside monitors, Nvidia is fixing what has been an unsolvable problem since the dawn of gaming.
Next: Color shift and overdrive