How Does G-SYNC Fix Stutters?

G-SYNC is a variable refresh rate technology. The refresh rate changes while gaming!

People are very surprised that you can have a fluctuating framerate without seeing any stutters. But, surprisingly, it is possible on a variable refresh rate display such as nVidia’s G-SYNC. These diagrams explain why nVidia G-SYNC eliminates erratic stutters, from the human vision perspective, when tracking eyes on moving objects on a monitor:

Without G-SYNC:
fps-vs-hz

With G-SYNC:
fps-vs-hz-gsync

As your eyes track a moving object at a constant speed, the positions of moving on-screen objects are now exactly where they are supposed to be, when using nVidia G-SYNC at any frame rate fluctuating within G-SYNC’s range (e.g. 30fps to 144fps). You do not see erratic stutters during variable-framerate motion.

There is, however, a very minor side effect: Variable motion blur.
– As framerates go down, your eyes perceive more motion blur. 
– As framerates go up, your eyes perceive less motion blur.
This effect is self-explanatory in the animations at www.testufo.com where lower framerates looks more blurry than higher framerates (on LCD displays).

How To Get G-SYNC?

See List of G-SYNC Monitors. Also discuss G-SYNC in the Blur Busters Forums!


3 Comments For “How Does G-SYNC Fix Stutters?”

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engineer123
Member
engineer123

Hi Chief,
excellent website and content, like it a lot. Kudos!
You wrote above: “G-SYNC does have a maximum refresh rate, so there’s a finite limit to how close the “dots” on the line can become on the third (last) diagram. This can cause divergences because of the slight divergence between frame time versus real world time.”

Can you explain that “in detail”? I’d like to know what G-Sync does and especially how it looks for the viewer when – on a 144 Hz monitor – the generated FPS by the graphics card reach 145 and more (be it 160, 180, 240 whatever)?
Does it cause tearing? Does G-Sync “automatically” switch to a VSync at 144 Hz (no tearing, but input lag and stutters)?

I’m especially interested in that point because the latest report at pcper.com about FreeSync on CES 2015 says something like “above 60 FPS on 60Hz monitor FreeSync switches to VSync while G-Sync does not behave the same way”.

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