G-SYNC 101: Range


Blur Buster's G-SYNC 101: Range Chart

Exceeds G-SYNC Range

G-SYNC + V-SYNC “Off”:
G-SYNC disengages, tearing begins display wide, no frame delay is added.

G-SYNC + V-SYNC “On”:
G-SYNC reverts to V-SYNC behavior when it can no longer adjust the refresh rate to the framerate, 2-6 frames (typically 2 frames; approximately an additional 33.2ms @60 Hz, 20ms @100 Hz, 13.8ms @144 Hz, etc) of delay is added as rendered frames begin to over-queue in both buffers, ultimately delaying their appearance on-screen.

G-SYNC + Fast Sync*:
G-SYNC disengages, Fast Sync engages, 0-1 frame of delay is added**.
*Fast Sync is best used with framerates in excess of 2x to 3x that of the display’s maximum refresh rate, as its third buffer selects from the “best” frame to display as the final render; the higher the sample rate, the better it functions. Do note, even at its most optimal, Fast Sync introduces uneven frame pacing, which can manifest as recurring microstutter.
**Refresh rate/framerate ratio dependent (see G-SYNC 101: G-SYNC vs. Fast Sync).

Within G-SYNC Range

Refer to “Upper & Lower Frametime Variances” section below…

Upper & Lower Frametime Variances

G-SYNC + V-SYNC “Off”:
The tearing inside the G-SYNC range with V-SYNC “Off” is caused by sudden frametime variances output by the system, which will vary in severity and frequency depending on both the efficiency of the given game engine, and the system’s ability (or inability) to deliver consistent frametimes.

G-SYNC + V-SYNC “Off” disables the G-SYNC module’s ability to compensate for sudden frametime variances, meaning, instead of aligning the next frame scan to the next scanout (the process that physically draws each frame, pixel by pixel, left to right, top to bottom on-screen), G-SYNC + V-SYNC “Off” will opt to start the next frame scan in the current scanout instead. This results in simultaneous delivery of more than one frame in a single scanout (tearing).

In the Upper FPS range, tearing will be limited to the bottom of the display. In the Lower FPS range (<36) where frametime spikes can occur (see What are Frametime Spikes?), full tearing will begin.

Without frametime compensation, G-SYNC functionality with V-SYNC “Off” is effectively “Adaptive G-SYNC,” and should be avoided for a tear-free experience (see G-SYNC 101: Optimal Settings & Conclusion).

G-SYNC + V-SYNC “On”:
This is how G-SYNC was originally intended to function. Unlike G-SYNC + V-SYNC “Off,” G-SYNC + V-SYNC “On” allows the G-SYNC module to compensate for sudden frametime variances by adhering to the scanout, which ensures the affected frame scan will complete in the current scanout before the next frame scan and scanout begin. This eliminates tearing within the G-SYNC range, in spite of the frametime variances encountered.

Frametime compensation with V-SYNC “On” is performed during the vertical blanking interval (the span between the previous and next frame scan), and, as such, does not delay single frame delivery within the G-SYNC range and is recommended for a tear-free experience (see G-SYNC 101: Optimal Settings & Conclusion).

G-SYNC + Fast Sync:
Upper FPS range: Fast Sync may engage, 1/2 to 1 frame of delay is added.
Lower FPS range: see “V-SYNC ‘On'” above.

What are Frametime Spikes?

Frametime spikes are an abrupt interruption of frames output by the system, and on a capable setup running an efficient game engine, typically occur due to loading screens, background asset streaming, network activity, and/or the triggering of a script or physics system, but can also be exacerbated by an incapable setup, inefficient game engine, poor netcode, low RAM/VRAM and page file over usage, misconfigured (or limited game support for) SLI setups, faulty drivers, specific or excess background processes, in-game overlay or input device conflicts, or a combination of them all.

Not to be confused with other performance issues, like framerate slowdown or V-SYNC-induced stutter, frametime spikes manifest as the occasional hitch or pause, and usually last for mere micro to milliseconds at a time (seconds, in the worst of cases), plummeting the framerate to as low as the single digits, and concurrently raising the frametime to upwards of 1000ms before re-normalizing.

G-SYNC eliminates traditional V-SYNC stutter caused below the maximum refresh rate by repeated frames from delayed frame delivery, but frametime spikes still affect G-SYNC, since it can only mirror what the system is outputting. As such, when G-SYNC has nothing new to sync to for a frame or frames at a time, it must repeat the previous frame(s) until the system resumes new frame(s) output, which results in the visible interruption observed as stutter.

The more efficient the game engine, and the more capable the system running it, the less frametime spikes there are (and the shorter they last), but no setup can fully avoid their occurrence.

Minimum Refresh Range

Once the framerate reaches the approximate 36 and below mark, the G-SYNC module begins inserting duplicate refreshes per frame to maintain the panel’s minimum physical refresh rate, keep the display active, and smooth motion perception. If the framerate is at 36, the refresh rate will double to 72 Hz, at 18 frames, it will triple to 54 Hz, and so on. This behavior will continue down to 1 frame per second.

Regardless of the reported framerate and variable refresh rate of the display, the scanout speed will always be a match to the display’s current maximum refresh rate; 16.6ms @60Hz, 10ms @100 Hz, 6.9ms @144 Hz, and so on. G-SYNC’s ability to detach framerate and refresh rate from the scanout speed can have benefits such as faster frame delivery and reduced input lag on high refresh rate displays at lower fixed framerates (see G-SYNC 101: Hidden Benefits of High Refresh Rate G-SYNC).



842 Comments For “G-SYNC 101”

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BlurBustersFans
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BlurBustersFans

i’m trying to setup G-Sync properly according to the optimal setting in this guide. In the game Call of Duty Warzone setting under custom FrameRate Limit I’ve set it to 138FPS because i have a 144hz gsync compatible monitor , next to this setting it has a text that says “Note that if Vsync is ON, your maximun framerate is still going to be your monitor’s refresh rate” . i turned on vsync in NVCP which this guide suggest. vsync Disabled in game setting. Does that mean the game engine will still limit my fps to 144 instead of 138? if so that is no good for gsync right ? because i want my fps to be a few fps below my monitor refresh rate
if i understand correctly. is there a way to verify if the game’s framerate limiter is capping my fps at 144 or 138 ? i have turned on the game’s fps counter , i see the counter fps number sometimes goes above 138. in between 140-142 and ocassiacionly reach 144 for like half a second and go back down. therefore i am not sure the in game fps limiter is working as intended. is the counter 100% accurate ? should i use NVCP’s frame cap instead? but that usually add more latency than in game’s setting and i dont want more latency. Any suggestions?

UPDATE: after some testing with the in game frame limit setting. it turns out the cap is working , i set the limit to 80 fps and the game indeed stay at around 80 fps reading from the in game fps counter, so it is not capping my fps at my monitor’s refresh rate with Vsync ON like the in-game description say , so i dont know why it says that. and i notice even tho i set it to 80 fps the fps counter fluctuated at around 78-83 just like when i set it to 189 it fluctuate between 136-143. so in this siutation do i trust the fps counter number? or should i set a number even lower than 138 so that i can guarantee the fps counter number would never go above my monitor’s refresh rate 144 to keep gysnc activated ?

nikoisconfused
Member
nikoisconfused

Hello! A week ago i bought a HP 24x G-SYNC compatible monitor , although im not fully sure if it works as intended. I am having issues with Dead By Daylight and the devs told me to lock the game at 60FPS , i did , and god its awful. I have tried everything , G-SYNC + VSYNC/G-SYNC ON + VSYNC OFF , nothing works and i have no idea why. On the Pendulum demo G-SYNC seems to be working perfectly , but sadly not in-game. Any ideas?

Zehdah
Member
Zehdah

I recently started playing older games, the main one being Elder Scrolls Oblivion at the moment and I play on a 144hz Gsync monitor. The game is locked to 60 FPS, going higher results in physics issues, so I am wondering if there are any particular settings I should be using in this situation for smooth gameplay. I’ve had people suggest turning Gsync off and Vsync on, which sounds like a strange thing to do to me, but I have no idea!

Mojoz
Member
Mojoz

Jorimt,

Thank you so much for this guide. It’s fantastic and you should be proud of how many people you’re helping here.

I just had a few questions I was hoping you could answer for me, to make sure I’m understanding this all correctly.

Notes: My monitor is an ASUS TUF Gaming VG259QM 240hz (overclockable to 280hz).

1. For competitive gaming, I should run G-Sync on and V-sync on (through Nvidia control panel) and cap my FPS 3 below my HZ. E.g. at 240hz I should cap at 237 FPS?

2. A follow-up question to this, what about capping FPS lower significantly lower than your HZ? Does it matter? For example, I’m currently playing Divinity Original Sin 2 and capping this at 120fps with 240hz (I rather have a stable FPS than have fluctuating 125-150fps). Is this okay or should I leave it uncapped?

3. Is more HZ better in every situation? My monitor is 240hz (overclockable to 270hz and 280hz). I was thinking of overclocking to 270hz (I’m not sure I want to run it at its limit). Does it matter if it’s not dividable by an even number (e.g. 270 and not 274 or 280). In your words, more Hz is better with g-sync right?

4. My monitor comes with something called “FreeSync” which can be used alongside G-Sync. I have no idea what this is. Should I just ignore it and leave it off?

Many, many thanks.

Mojoz

Nsnake771
Member
Nsnake771

Hi guys,
I recently played R6s Vulkan and as I do with every other games, I set on NVCP the max frame rate to 141, but it didn’t work in-game. Does the max frame rate featured doesn’t work on Vulkan games ?

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