Very simply put, the graphics card is always firing off frames as fast as it can possibly do, that FPS this is dynamic and can bounce from say 30 to 80 FPS in a matter of split seconds. On the eye side of things, you have this hardware which is the monitor and it is a fixed device as it refreshes at 60 Hz (60Hz is an example). Fixed and Dynamic are two different things and collide with each other. So on one end we have the graphics card rendering at a varying framerate while the monitor refreshes at 60 images per second. That causes a problem as with a slower or faster FPS then 60 you'll get multiple images displayed on the screen per refresh of the monitor. So graphics cards don’t render at fixed speeds. In fact, their frame rates will vary dramatically even within a single scene of a single game, based on the instant load that the GPU sees.
In the past we solved problems like Vsync stutter and Tearing basically in two ways. The first way is to simply ignore the refresh rate of the monitor altogether, and update the image being scanned to the display in mid cycle. This you guys all know and have learned as ‘VSync Off Mode’ it is the default way most gamers play. The downside is that when a single refresh cycle show 2 images, a very obvious “tear line” is evident at the break, yup, we all refer to this as screen tearing. You can solve tearing though.
The solution to bypass tearing is to turn VSync on, here you will force the GPU to delay screen updates until the monitor cycles to the start of a new refresh cycle. That delay causes stutter whenever the GPU frame rate is below the display refresh rate. Iit also increases latency, which is the direct result for input lag, the visible delay between a button being pressed and the result occurring on-screen.
Enabling VSYNC helps a lot, but with the video card firing off all these images per refresh you can typically see some pulsing (I don't wanna call it vsync stuttering) when that framerate varies and you pan from left to right in your 3D scene. So that is not perfect.
Alternatively most people disable VSYNC - but that runs into a problem as well, multiple images per refreshed Hz will result into the phenomenon that is screen tearing, which we all hate.
Basically this is why we all want extremely fast graphics cards as most of you guys want to enable VSYNC and have a graphics card that runs faster then 60 FPS.
What is the solve ?
Nvidia is releasing G-Sync. Now as I explained the graphics card is running dynamic Hz, the monitor is static Hz, these two don't really match together. G-Sync is both a software and a hardware solution that will solve screen tearing and stuttering. A daughter hardware board (it actually looks a little like a mobile MXM module) is placed into a G-Sync enabled monitor which will do something very interesting. With G-Sync the monitor will become a slave to your graphics card as the its refresh rate in Hz becomes dynamic. Yes, it is no longer static. So each time your graphics card has rendered one frame that frame is aligned up with the monitor refresh rate. So the refresh rate of the monitor will become dynamic. With both the graphics card and monitor both dynamically in sync with each other you have eliminated stutter and screen tearing completely.
It gets even better, without stutter and screen tearing on an nice IPS LCD panel even at 30+ Hz you'd be having an incredibly good gaming experience (visually). BTW monitors upto 177 hz will get supported with Gsync as well as 4K monitors.
Summed up : NVIDIA G-SYNC is a solution that pretty much eliminates screen tearing, VSync input lag, and stutter. You need a G-SYNC module into monitors, allowing G-SYNC to synchronize the monitor to the output of the GPU, instead of the GPU to the monitor, resulting in a tear-free, faster, smoother experience.
