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G-SYNC 101: Control Panel

Published Jun 20, 2017 by in: G-SYNC

G-SYNC Module

The G-SYNC module is a small chip that replaces the display’s standard internal scaler, and contains enough onboard memory to hold and process a single frame at a time.

The module exploits the vertical blanking interval (the span between the previous and next frame scan) to manipulate the display’s internal timings; performing G2G (gray to gray) overdrive calculations to prevent ghosting, and synchronizing the display’s refresh rate to the GPU’s render rate to eliminate tearing, along with the delayed frame delivery and adjoining stutter caused by traditional syncing methods.

G-SYNC Demo

The below Blur Busters Test UFO motion test pattern uses motion interpolation techniques to simulate the seamless framerate transitions G-SYNC provides within the refresh rate, when directly compared to standalone V-SYNC.

G-SYNC Activation

“Enable for full screen mode” (exclusive fullscreen functionality only) will automatically engage when a supported display is connected to the GPU. If G-SYNC behavior is suspect or non-functioning, untick the “Enable G-SYNC, G-SYNC Compatible” box, apply, re-tick, and apply.

Blur Buster's G-SYNC 101: Control Panel

G-SYNC Windowed Mode

“Enable for windowed and full screen mode” allows G-SYNC support for windowed and borderless windowed mode. This option was introduced in a 2015 driver update, and by manipulating the DWM (Desktop Windows Manager) framebuffer, enables G-SYNC’s VRR (variable refresh rate) to synchronize to the focused window’s render rate; unfocused windows remain at the desktop’s fixed refresh rate until focused on.

G-SYNC only functions on one window at a time, and thus any unfocused window that contains moving content will appear to stutter or slow down, a reason why a variety of non-gaming applications (popular web browsers among them) include predefined Nvidia profiles that disable G-SYNC support.

Note: this setting may require a game or system restart after application; the “G-SYNC Indicator” (Nvidia Control Panel > Display > G-SYNC Indicator) can be enabled to verify it is working as intended.

G-SYNC Preferred Refresh Rate

“Highest available” automatically engages when G-SYNC is enabled, and overrides the in-game refresh rate selector (if present), defaulting to the highest supported refresh rate of the display. This is useful for games that don’t include a selector, and ensures the display’s native refresh rate is utilized.

“Application-controlled” adheres to the desktop’s current refresh rate, or defers control to games that contain a refresh rate selector.

Note: this setting only applies to games being run in exclusive fullscreen mode. For games being run in borderless or windowed mode, the desktop dictates the refresh rate.

G-SYNC & V-SYNC

G-SYNC (GPU Synchronization) works on the same principle as double buffer V-SYNC; buffer A begins to render frame A, and upon completion, scans it to the display. Meanwhile, as buffer A finishes scanning its first frame, buffer B begins to render frame B, and upon completion, scans it to the display, repeat.

The primary difference between G-SYNC and V-SYNC is the method in which rendered frames are synchronized. With V-SYNC, the GPU’s render rate is synchronized to the fixed refresh rate of the display. With G-SYNC, the display’s VRR (variable refresh rate) is synchronized to the GPU’s render rate.

Upon its release, G-SYNC’s ability to fall back on fixed refresh rate V-SYNC behavior when exceeding the maximum refresh rate of the display was built-in and non-optional. A 2015 driver update later exposed the option.

This update led to recurring confusion, creating a misconception that G-SYNC and V-SYNC are entirely separate options. However, with G-SYNC enabled, the “Vertical sync” option in the control panel no longer acts as V-SYNC, and actually dictates whether, one, the G-SYNC module compensates for frametime variances output by the system (which prevents tearing at all times. G-SYNC + V-SYNC “Off” disables this behavior; see G-SYNC 101: Range), and two, whether G-SYNC falls back on fixed refresh rate V-SYNC behavior; if V-SYNC is “On,” G-SYNC will revert to V-SYNC behavior above its range, if V-SYNC is “Off,” G-SYNC will disable above its range, and tearing will begin display wide.

Within its range, G-SYNC is the only syncing method active, no matter the V-SYNC “On” or “Off” setting.

Currently, when G-SYNC is enabled, the control panel’s “Vertical sync” entry is automatically engaged to “Use the 3D application setting,” which defers V-SYNC fallback behavior and frametime compensation control to the in-game V-SYNC option. This can be manually overridden by changing the “Vertical sync” entry in the control panel to “Off,” “On,” or “Fast.”

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3751 Comments For “G-SYNC 101”

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S1YI
Member
S1YI

Hello! So i have a 75 hertz monitor and i was wondering what would be the best method to not get screen tear(im ok with a little) and have the least amount of input lag. I have tried capping my frames to 60 and 72 and i still get screen tear. I get an average of 250 without capping them and get terrible screen tear. My monitor is also freesync which works with gsync(i have a nvidia gpu). Would the best thing to cap at 72 and run gsync or run gsync with vsync.

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4 years 9 months ago
jorimt
Author
jorimt

Two options:

– RTSS Scanline Sync: https://forums.blurbusters.com/viewtopic.php?f=2&t=4173&start=70#p36230

OR

– G-SYNC + NVCP V-SYNC + minimum 72 FPS limit.

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4 years 9 months ago
m.eshi
Member
m.eshi

Hi. I’ve been blindly using gsync with vsync off since 2017! this was extremely informative and helpful.
However, I have 2 questions for which I couldn’t find a direct answer for
1. can fullscreen optimization cause gsync not to function when you only enable it for fullscreen and not windowed?
2. does enabling vsync on top of gsync cause a performance hit compared to gsync alone?

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4 years 9 months ago
m.eshi
Member
m.eshi

Great! thanks a lot

Like1Vote Down 
4 years 9 months ago
jorimt
Author
jorimt

1. Not that I’m aware of, but if you only enable G-SYNC for fullscreen, it won’t engage in borderless/windowed mode (though I recommend per app override for that anyway; see my Closing FAQ for an entry on that).
2. No, not within the refresh rate. The only difference between G-SYNC on + V-SYNC off and G-SYNC on + V-SYNC on is the former can tear, and the latter can’t.

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4 years 9 months ago
king.z
Member
king.z

Hi! Amazing article! Just got into the high refresh rate bandwagon just a few months ago and this really helped me get the most out of my gaming set up.

I own an Asus ROG XG279Q 170hz (overclocked) gaming monitor. Currently it is set to 165hz just to be “safe”. Anyway I’m just curious, setting aside screen tearing, what happens if I turn off both gsync & vsync then limit my frames to 165 fps? Will that result on high input lag compared to gsync + vysnc on and frames limited to 162 fps? I’m sorry in advance though if this was already asked before.

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4 years 9 months ago
jorimt
Author
jorimt

You’ll get tearing, and the lowest possible input lag in that scenario due to said tearing.

That said, if you’re going to do that, you should play uncapped. This will reduce tearing artifacts and input lag further, assuming you’re system can sustain 2x or more framerate above your refresh rate in the given game.

If not, and your GPU maxes out at that framerate (and you’re not using a game that supports Reflex), you’ll incur render queue input lag (entirely separate from V-SYNC input lag), at which point you’ll want to limit your FPS to your 99% achievable average, but if that average is within your refresh rate and you don’t like tearing artifacts, you’re better off re-enabling G-SYNC + V-SYNC with the FPS limit, as that will prevent tearing and V-SYNC input lag, and create smoother frame delivery, all the while having less than <1ms more input lag than G-SYNC off + V-SYNC off in the same scenario.

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4 years 9 months ago
king.z
Member
king.z

Thank you so much! That cleared things up for me 100%

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4 years 9 months ago
Nsnake771
Member
Nsnake771

hi, here is my question : it has been a while now that i use the optimal/recommanded settings shown in this thread. For example, I play warzone/Modern warfare and R6 siege with vsync enabled in the NVCP along with Gsync. I’ve also applied a fps limit directly from the games files.

Recently nvidia reflex has been added to r6 siege with today’s update, and i would like to know if reflex is compatible with the low latency mode, and by ” low latency mode” i mean, the fact of reducing the frame by 3, for example i play wz and R6 with a fps limit of 141, bcause my monitors max refresh rate is 144. i am asking this question because when playing Modern warfare i did some test, and when I enabled nvidia reflex I obtained slightly worse result in terms of gpu and cpu latency time, and on top of that with reflex enabled i also noticed a strange feeling, as if it was less smoth, with some stutters. So that is my concerns, given that I use the optimal settings shown in this guide, is it still relevant to use reflex, especially on r6, are these settings and nvidia relfex conflictive ?

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4 years 9 months ago
jorimt
Author
jorimt

Short answer: No, they don’t conflict; at best, they compliment each other, at worst, they address different aspects of latency.

I know when you say “low latency mode,” you’re referring to the -3 fps limit with G-SYNC, but Reflex does actually replace “Low Latency Mode” (both “On” and “Ultra”) in the Nvidia Control Panel. E.g. if you have LLM and Reflex enabled, only Reflex will take effect.

As for Reflex itself, it eliminates the render queue, which primarily applies when your GPU usage is maxed, at which point it typically means whatever static FPS limit you have set isn’t being reached, and the framerate then fluctuates below it, typically signifying your GPU usage is maxed (99% >), which increases the pre-rendered frames queue, which, in turn, increases buffer lag separate of the V-SYNC lag that G-SYNC fixes.

Reflex addresses this by effectively setting a dynamic FPS limit just enough below the fluctuating framerate to prevent maxing the usage of the GPU, and thus keeping the pre-rendered frames queue empty.

Other than this, like G-SYNC + V-SYNC + LLM “Ultra” before it, with G-SYNC + NVCP V-SYNC enabled (and when the GPU isn’t maxed), Reflex sets an auto FPS limit slightly below the refresh rate to keep it in range (at 144Hz, it limits around ~138).

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4 years 9 months ago
Nsnake771
Member
Nsnake771

thx you a lot jorimt, yeah I understood now, i just did some research about how reflex work and i better understand your explanation. So if i am not wrong, until now, by reducing the fps by minus 3 (in my case), what we concretly were trying to do was to reduce as much as possible the pre rendered frames queue and thus reducing gpu usage etc. And reflex is basically the same method but directly implemented into the game by the dev, which should make it more efficient. so basically they both do more or less the same but reflex is an enhanced version.

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4 years 9 months ago
jorimt
Author
jorimt

Close, but not quite…

G-SYNC’s primary intent where latency is concerned, is to prevent V-SYNC input lag. You do this by keeping the framerate within the refresh rate by setting a minimum -3 FPS limit.

As for render queue lag, G-SYNC really only prevents that by coincidence, say if you have a 144Hz monitor, and your particular GPU can sustain the framerate at that ~141 FPS limit while retaining GPU overhead (aka not maxing out), but that’s not it’s direct goal.

In fact, if you have, say, a static 141 FPS limit via an in-game or external limiter, but your current framerate isn’t reaching it (because your GPU is maxed), G-SYNC is preventing V-SYNC input lag, but it is not preventing render queue input lag.

Without G-SYNC, Reflex tries to address render queue input lag in GPU-bound situations.

With G-SYNC, Reflex tries to address both render queue input lag and V-SYNC input lag, by 1) preventing max GPU usage during fluctuating framerates by setting a dynamic FPS limit just below the fluctuating average framerate (like it does for non-G-SYNC scenarios), and 2) when your GPU isn’t maxed, and the framerate can reach a static set limit, Reflex sets an automatic static limit slightly below your current max refresh rate to keep G-SYNC within it’s range, thus preventing V-SYNC input lag (assuming you’re using G-SYNC + V-SYNC).

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4 years 9 months ago
Nsnake771
Member
Nsnake771

Thank you again for your explanations Jorimt. Let’s now imagine the following scenario. I am playing Owerwatch or R6 with Gsync + NVCP Vsync, full screen, and i easily maintain my framerate to 141 (141 beeing the in game fps limit that I have set). In that scenario, what other benefits would i get from enabling Nvidia’s Reflex ?

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4 years 9 months ago
jorimt
Author
jorimt

If the framerate never dipped below the limit and your GPU usage stayed below max?

In that case, there would be virtually no benefit in using Reflex.

You could leave it on in the rare cases that your FPS does dip below the limit though.

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4 years 9 months ago
Miro
Member
Miro

The g sync work perfectly with the Low Latency Mode set on ULTRA ?

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4 years 9 months ago
jorimt
Author
jorimt

I’m going to need more context to answer that.

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4 years 9 months ago
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