NVIDIA G-Sync

Last month, NVIDIA invited the European press to a special event in London, where it demonstrated G-Sync, a new technology by NVIDIA that addresses monitor-stuttering issues that were deemed unsolvable.



For archaic reasons, such as being evolved essentially off television sets, PC monitors feature fixed refresh-rates, the number of times a display refreshes what it is displaying per second. There's no technical reason why a modern flat-screen display should feature fixed refresh rates. Since it's the displays that dictate refresh rates, it has always been the GPU's job to ensure display output is fluid, which it did by deploying technologies such as V-Sync (vertical sync). If a GPU sends out lower number of frames per second than the display refresh rate, the output won't appear fluid. If it sends higher number of frames per second, the output would feature artifacts such as display-tearing, caused by portions of multiple frames overlapping each other.



NVIDIA's solution to the problem is to kill fixed refresh rates on monitors, instead making them synchronize their refresh rates in real-time to the frame-rates generated by a GPU. Ever wondered why a movie watched in a theater feels more fluid at even 24 frames per second while a PC game being played at that frame-rate doesn't? It's because the monitor mandates that the GPU obey its refresh-rate. G-Sync tilts that equation and makes the monitor sync its refresh-rate to the frame-rate of the GPU so games will feel more fluid at frame-rates well below 60. To make this happen, NVIDIA developed hardware that resides inside the display—hardware that communicates with the GPU in real-time to coordinate G-Sync.



We've witnessed G-Sync with our own eyes at the London event and couldn't believe what we were seeing. Games (playable, so we could tell they weren't recordings) were butter-smooth and extremely fluid. At the demo, NVIDIA displayed games that were doing 40 to 59 FPS in a given scene, and it felt like a constant frame-rate throughout. NVIDIA obviously demonstrated cases where G-Sync unleashed its full potential—on FPS between 35 and 59. I am still a bit skeptical because it looks too good to be true, so I'm looking forward to testing G-Sync on my own setup and with my own games, mouse and keyboard included, for a complete assessment. One can't make a video recording of a display that's running G-Sync to show you that, and you really need to experience G-Sync to buy into the idea. NVIDIA's G-Sync will launch with a $100 price premium on monitors. That's not insignificant, but could also go down in the future. Also, from what I've seen, G-Sync promises lower framerates that look smoother, which means you no longer need an expensive card to reach 60 FPS—money you then put into a G-Sync enabled monitor instead.

NVIDIA Shadow Play

GeForce Experience Shadow Play is another feature NVIDIA recently debuted. The feature lets you create video recordings or live-streams of your gameplay with minimal performance impacts on the game you're playing. The feature is handled by GeForce Experience, which lets you set hot-keys to toggle recording on the fly; or the output, format, quality, and so on.



Unlike other apps, which record videos at loss-less AVI formats by tapping into the DirectX pipeline and clogging the system bus, disk, and memory with high bit-rate video streams, Shadow Play taps into a proprietary path that lets it copy the display output to the GPU's hardware H.264 encoder. This encoder neither strains the CPU nor the GPU's own unified shaders. Since the video stream that's being saved to a file comes out encoded, its bit-rate is infinitesimally lower than uncompressed AVI.