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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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3696 Comments For “G-SYNC 101”

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lmyx
Member
lmyx

The RTSS FPS limiter (or any FPS limiter for that matter, in-game or external) is only active when the framerate is sustained above the set FPS limit. Whenever the framerate drops below the set limit, the limiter is effectively inactive until the framerate is once again sustained above it.

Does it mean that if I set in-game frame limiter to let’s say -5 frames of monitor frequency and also set NVCP Max Frame Rate setting to -2 frames, in such scenario only in-game limiter would work?
I would like to set NVCP Max Frame Rate globally and use it as precautionary measure in case game does not have in-game limiter or I forget to set it.

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3 months 14 days ago
jorimt
Author
jorimt

General rule is lower limit takes effect over higher limit, regardless of limiting method.

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3 months 14 days ago
Ghokury
Member
Ghokury

What do you think about this topic ?

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3 months 15 days ago
jorimt
Author
jorimt

Regarding:

The old “3 or 4 under your refresh rate” FPS cap from Blur Busters is outdated and incorrect.

I don’t recommend “3 or 4 under your refresh rate,” I recommend a minimum 3 FPS limit below the currently set physical refresh rate. I.E. it’s a baseline starting point and anyone is free to limit below it.

Even a -2 FPS limit in my original tests with in-game and external limiters was sufficient in keeping the average framerate within the refresh rate at 240Hz, but yes, the higher the refresh rate (especially 240Hz+), the lower the framerate limit you may need to keep VRR engaged at all times, especially the worse the frametime performance of the given game/limiter.

Frametime performance is key, and can vary wildly from system-to-system, and even from game-to-game on the same system.

Feel free to utilize their “Refresh – (Refresh x Refresh / 3600) = FPS Cap” formula, where desired.

Like2Vote Down 
3 months 15 days ago
user2422
Member
user2422

when using gsync + vsync what is “better” manual in game fps cap 3 below refresh rate or reflex?

what would be the best competitive low latency tear free setup?

are there differences in latency, frame times or 1%/0.1% lows between the two?

and when using reflex as the cap should i uncap my fps in game or keep the manual fps cap as a backup?

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3 months 17 days ago
jorimt
Author
jorimt

when using gsync + vsync what is “better” manual in game fps cap 3 below refresh rate or reflex?

Situational; depends on whether your system is GPU-bound in the given game.

what would be the best competitive low latency tear free setup?

G-SYNC + NVCP V-SYNC + manual in-game FPS limit (at least 3 frames within the physical refresh rate) that prevents 99%+ GPU usage at all times.

are there differences in latency, frame times or 1%/0.1% lows between the two?

Latency-wise, no, since they’re both at the engine-level:
https://forums.blurbusters.com/viewtopic.php?p=72633#p72182

As for 0.1 to 1% lows, I personally avoid Reflex if my game isn’t GPU-bound at my target average framerate…

Reflex monitors GPU usage at the current average framerate, and then sets its dynamic limiter slightly below that whenever the GPU usage would otherwise become 99%+, so hypothetically, it could try to limit the framerate during frametime spikes (which are effectively 0 FPS for a frame or more at a time), elongating them slightly over a manual limit, which instead stays what it’s set to, regardless of GPU usage or frametime performance.

So my general rule is to only use Reflex in games that are predominately GPU-bound, and, as such, may frequently dip below a target average framerate.

I.E. let’s say you have a 240Hz monitor with a game that has both an in-game limiter and Reflex available, but the highest average framerate your system can sustain is 120 FPS, and the more demanding scenes can still occasionally drop below your target 120 FPS; you can set a manual in-game limit of 120 FPS AND enable Reflex, in which case, the 120 FPS in-game limit will keep it at your target average, but will fall back to Reflex’s dynamic limiter whenever a more demanding scene causes the GPU usage to max and the average framerate to drop below that 120 FPS target.

and when using reflex as the cap should i uncap my fps in game or keep the manual fps cap as a backup?

Refer to the above.

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3 months 17 days ago
user2422
Member
user2422

when using this recommended setup in my case gsync on + vsync on + in-game 162 fps cap should low latency mode be set to on in case my fps drops below 162 in a gpu bound situation? and what if my fps drops because im cpu bound?

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3 months 17 days ago
jorimt
Author
jorimt

when using this recommended setup in my case gsync on + vsync on + in-game 162 fps cap should low latency mode be set to on in case my fps drops below 162 in a gpu bound situation?

You can, but it’s not as effective as Reflex at preventing GPU-bound latency, and may or may not elongate frametime variances and spikes (aka potentially worse 0.1 to 1% lows compared to LLM off).

what if my fps drops because im cpu bound?

CPU bottlenecks limit maximum possible GPU usage, and thus reduce maximum possible average framerate, so the only latency “penalty” is typically just that; a lower average framerate compared to if the GPU wasn’t bottlenecked by the CPU.

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3 months 16 days ago
leovaz
Member
leovaz

Hey! So, there is a specific game that I play with FPS uncapped. I’d like to know if there’s any downside of having g-sync on in that case, as the game will constantly hover over the g-sync range turning it on and off during the match.

I dont have any tearing in this game, but turning off G-sync on NVCP for that specific game makes alt tabing really annoying as my monitor keeps flasing when doing it. That is way I’d like to know if keeping g-sync on even without a FPS limit could cause me some problem (with frame time, input latency, etc).

Thanks in advance!

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3 months 23 days ago
jorimt
Author
jorimt

That is way I’d like to know if keeping g-sync on even without a FPS limit could cause me some problem (with frame time, input latency, etc).

Unlikely; the only time G-SYNC will engage in that scenario is whenever the average framerate drops below the physical refresh rate or momentarily during any frametime spikes.

And in those cases, with G-SYNC on + V-SYNC off, it still allows tearing within the refresh rate, so it should have very little effect (if any) over G-SYNC off.

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3 months 22 days ago
nanasister
Member
nanasister

Hi, great guide! I have a quick follow-up question. Apologies if this has already been asked.

So, from what I understand, G-Sync makes your monitor match its refresh rate to your in-game FPS — like if you’re getting 120 FPS, the monitor runs at 120 Hz — to prevent screen tearing.

If that’s the case, then for games that are locked at 60 FPS, does G-Sync make the monitor run at 60 Hz? And if so, does that mean the game would feel less smooth, kind of like playing on a low refresh rate monitor?

One more thing I’m wondering about: I turned on the refresh rate display on my monitor while G-Sync was enabled, and I noticed the refresh rate kept jumping around — it wasn’t stable. For example, in a game running at 60 FPS, the refresh rate was fluctuating between around 40 to 70 Hz instead of staying steady at 60 Hz.

Is that normal?

Thanks.

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3 months 24 days ago
jorimt
Author
jorimt

So, from what I understand, G-Sync makes your monitor match its refresh rate to your in-game FPS — like if you’re getting 120 FPS, the monitor runs at 120 Hz — to prevent screen tearing.

If that’s the case, then for games that are locked at 60 FPS, does G-Sync make the monitor run at 60 Hz? And if so, does that mean the game would feel less smooth, kind of like playing on a low refresh rate monitor?

I actually covered this in the comment directly below yours; VRR will limit the amount of times the scanout cycle repeats per second to 60 at 60 FPS, while the monitor continues to scan in each frame at the scanout speed of the currently set physical refresh rate.

So yes, for all intents and purposes, it will look and behave like a physical 60Hz (the mouse cursor will update at that rate as well), but it will feel more responsive the higher the physical refresh rate due to the increased scanout speed.

I.E. 120Hz 60 FPS VRR is more responsive than 60Hz 60 FPS VRR, and 240Hz 60 FPS VRR is even more responsive than 120Hz 60 FPS VRR, and so on; the higher physical refresh rate, the better with VRR, regardless of achievable average framerate.

One more thing I’m wondering about: I turned on the refresh rate display on my monitor while G-Sync was enabled, and I noticed the refresh rate kept jumping around — it wasn’t stable. For example, in a game running at 60 FPS, the refresh rate was fluctuating between around 40 to 70 Hz instead of staying steady at 60 Hz.

Is that normal?

It’s entirely normal. Many have asked the same here and in the forums….

Monitor-side variable refresh rate meters are approximated (especially the G-SYNC Compatible FreeSync variants) and are only useful for determining whether VRR is currently engaged; static number at the current physical refresh rate = un-engaged, fluctuating at a number below the current physical refresh rate = engaged.

They are worthless for accurate moment-to-moment VRR/framerate readings, and will often include LFC multiples in the readout (further throwing off the actual effective VRR number). Use system-side readouts for average frametime/framerate readings instead.

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3 months 23 days ago
wpDiscuz

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