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.



1716 Comments For “G-SYNC 101”

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Joselaba97
Member
Joselaba97

Just wanted to say thank you for the prolonged work and research you’ve been putting into your findings.

I have some questions and concerns regarding, multi-display configurations utilizing discordanant refresh rates, while one of them being gsync compatible, and also while utilizing DX12 applications with OBS game capture. I’ve also noticed that a good amount of DX12 games have been implementing reflex and other gsync compatibility optimizations as well, so this has expanded the amount of variables to consider for minimal input latency implementations.

For Gears 5, I utilize the NVCP vsync, the internal frame cap system (144 fps), gsync-compatible: full-screen mode only, and the reduced buffering option. However, I’m concerned as to what gsync and vysnc implementation should be used together, specifically the full-screen/full-screen & windowed mode and ON, OFF, Fast, and 3D application setting, respectively. I often stream the game and have noticed a considerable amount of input lag w/ occasional stutters with that concurrent configuration, regardless of the fact that it should be the configuration with the least amount of input lag. I’ve considered that it’s probably due to the secondary 60Hz monitor, but that is essential since it’s utilized to monitor chat and other related tasks while gaming on my 240Hz g-sync compatiable monitor. I also minimize OBS to the system tray in order to ensure that no hardware-accelerated tasks are interfering with the actively rendering game and its respective frame-pacing system.

Also, given that Nvidia has begun implementing optimizations for LLM and gysnc & vsync, is ULLM an option to consider regardless of the RB setting in-game?
Is there something that I have personally overlooked w/ respect to NVCP and the game?
Should I consider using the fixed refresh rate instead? (240Hz, I currently have the NVCP set to Prefer highest refresh rate)
Are there any setting recommendations that you would recommend for my current application? (w/ respect to windows settings, NVCP, and in-game)

Conclusively, gsync has been more of a headache to handle with rather than a “cool” optimization to use in-game. So I ask if you could please provide me with any information regarding my current application and optimization suggestions. Thank you

grumpycalabi314
Member
grumpycalabi314

Hi! First of all thanks for all the work you do. I noticed that if i play Battlefield (4 or 1) and if i set an FPS cap to 138 via NVCP, the game doesn’t feel quite right. I also noticed that the in-game fps counter (perfoverlay.drawfps 1) isn’t really stable (it stays a lot a 139, and jumps even at 141). On the other end, if i set an ingame fps limiter (gametime.maxvariablefps 138), the ingame fps counter is much more stable, always stays at 138 and the game feels much better. Have you done some testing on the frostbite engine to confirm or not this?
PS: VSYNC was set to ON via NVCP
Thanks you for the help.

chron42
Member
chron42

Hi, if I globally set the “Max frame rate” in Nvidia Control Panel to 141 (-3 FPS to my refresh rate), will this introduce the <1 Frame Delay to games where an in-game FPS limiter is available? (Using the in-game limiter I also set the game to max 141 FPS)

Niko
Member
Niko

Hello there, i play destiny 2 a lot and i cant seem to fix this weird stutter i play on a 1080ti and a 8700k oc to 5.0ghz with a 180 hz asus gsync monitor i have all my settings on low and i have gsync enables vsync enabled in nvcp and reflex on in the cvar files, the game just does not feel smooth reflex caps it to about 171 and it just bounces around between 145-171 its super frustrating

NNSLKPTIS
Member
NNSLKPTIS

Hello, sry for my engl. I have a Alienware aw2521hf 240hz and 1070. Usually Im playing Warzone. Please help me with settings for lowest input lag.
NVCP G-sync on
NVCP V-SYNC on.input lag is more lower then off right ?
nvidia reflex on + boost
should I use NVCP low latency mode? because game support nvidia reflex.
and limit maximum refresh rate in game 237 or nvcp 237 ? my fps around 90-110.
Thanks you for the help.

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