G-SYNC 101: G-SYNC vs. V-SYNC OFF


Beyond the Limits of the Scanout

It’s already been established that single, tear-free frame delivery is limited by the scanout, and V-SYNC OFF can defeat it by allowing more than one frame scan per scanout. That said, how much of an input lag advantage can be had over G-SYNC, and how high must the framerate be sustained above the refresh rate to diminish tearing artifacts and justify the difference?

Blur Buster's G-SYNC 101: Input Latency & Optimal Settings
Blur Buster's G-SYNC 101: Input Latency & Optimal Settings
Blur Buster's G-SYNC 101: Input Latency & Optimal Settings
Blur Buster's G-SYNC 101: Input Latency & Optimal Settings
Blur Buster's G-SYNC 101: Input Latency & Optimal Settings
Blur Buster's G-SYNC 101: Input Latency & Optimal Settings

Quite high. Counting first on-screen reactions, V-SYNC OFF already has a slight input lag advantage (up to a 1/2 frame) over G-SYNC at the same framerate, especially the lower the refresh rate, but it actually takes a considerable increase in framerate above the given refresh rate to widen the gap to significant levels. And while the reductions may look significant in bar chart form, even with framerates in excess of 3x the refresh rate, and when measured at middle screen (crosshair-level) only, V-SYNC OFF actually has a limited advantage over G-SYNC in practice, and most of it is in areas that one could argue, for the average player, are comparatively useless when something such as a viewmodel’s wrist is updated 1-3ms faster with V-SYNC OFF.

This is where the refresh rate/sustained framerate ratio factors in:

Blur Buster's G-SYNC 101: Input Latency & Optimal Settings
Blur Buster's G-SYNC 101: Input Latency & Optimal Settings
Blur Buster's G-SYNC 101: Input Latency & Optimal Settings

As shown in the above diagrams, the true advantage comes when V-SYNC OFF can allow not just two, but multiple frame scans in a single scanout. Unlike syncing solutions, with V-SYNC OFF, the frametime is not paced to the scanout, and a frame will begin scanning in as soon as it’s rendered, regardless whether the previous frame scan is still in progress. At 144Hz with 1000 FPS, for instance, this means with a sustained frametime of 1ms, the display updates nearly 7 times in a single scanout.

In fact, at 240Hz, first on-screen reactions became so fast at 1000 FPS and 0 FPS, that the inherit delay in my mouse and display became the bottleneck for minimum measurements.

So, for competitive players, V-SYNC OFF still reigns supreme in the input lag realm, especially if sustained framerates can exceed the refresh rate by 5x or more. However, while at higher refresh rates, visible tearing artifacts are all but eliminated at these ratios, it can instead manifest as microstutter, and thus, even at its best, V-SYNC OFF still can’t match the consistency of G-SYNC frame delivery.



2231 Comments For “G-SYNC 101”

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Vasko
Member
Vasko

Hello,

Would you please recommend the lowest latency setting for my pc in COD Cold War? I have the 360Hz Asus monitor and get between 280-310 fps during game play. I currently have the monitor set at 240Hz with unlimited fps, V-Sync and G-Sync off and it is very smooth. Would it be better to change the refresh rate to 300 or 360Hz even though the fps most likely average around 280? Does it make sense to turn G-Sync on?

Your help is highly appreciated!

Thank you,
Vasko

Tonaway
Member
Tonaway

Hello, I have a weird question.

Does G-SYNC still work if you lower the refresh rate (to something inside G-SYNC range) and use V-SYNC on in order to lock the FPS? Instead of running max refresh rate + V-SYNC on + -3 FPS lock.

For example: set refresh rate from 144hz to 120hz and activate V-SYNC so the game runs at 120 FPS and hz. In this case, will G-SYNC still be active? Or do you still have to set a FPS limiter to 117 FPS?

Will these settings have G-SYNC working as intended or will there be detriments to running games like this (except for running it at 120hz and 120 FPS, instead of 144hz and 141 FPS). If it works, does locking the FPS this way have any benefit over other ways of locking the FPS, and does it introduce normal V-SYNC latency if it hits 120 FPS?

fatehasfans
Member
fatehasfans

Hi there, is there an optimizing guide for Free-sync?

gaxode9376
Member
gaxode9376

what if a game only let you cap at a fixed refresh rate or unlimited rather than a custom value

DerConnor
Member
DerConnor

So what actually causes the tearing from “Upper & Lower Frametime Variances”? Is it because G-Sync is somehow unable to respond to a quick change in frametime (I read somewhere it uses a fixed polling frequency to update the current refresh rate)? And in the Valorant clips with the FPS capped to 142, shouldn’t this result in a constant frametime or is there some problem with how the FPS limiter works (introducing inconsistent frametimes)? I also can’t for the life of me see any tearing in the second Valorant clip.

Thanks a lot for this article, it was a super interesting and informative read.

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