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


Identical or Fraternal?

As described in G-SYNC 101: Range, G-SYNC doesn’t actually become double buffer V-SYNC above its range (nor does V-SYNC take over), but instead, G-SYNC mimics V-SYNC behavior when it can no longer adjust the refresh rate to the framerate. So, when G-SYNC hits or exceeds its ceiling, how close is it to behaving like standalone V-SYNC?

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

Pretty close. However, the G-SYNC numbers do show a reduction, mainly in the minimum and averages across refresh rates. Why? It boils down to how G-SYNC and V-SYNC behavior differ whenever the framerate falls (even for a moment) below the maximum refresh rate. With double buffer V-SYNC, a fixed frame delivery window is missed and the framerate is locked to half the refresh rate by a repeated frame, maintaining extra latency, whereas G-SYNC adjusts the refresh rate to the framerate in the same instance, eliminating latency.

As for “triple buffer” V-SYNC, while the subject won’t be delved into here due to the fact that G-SYNC is based on a double buffer, the name actually encompasses two entirely separate methods; the first should be considered “alt” triple buffer V-SYNC, and is the method featured in the majority of modern games. Unlike double buffer V-SYNC, it prevents the lock to half the refresh rate when the framerate falls below it, but in turn, adds 1 frame of delay over double buffer V-SYNC when the framerate exceeds the refresh rate; if double buffer adds 2-6 frames of delay, for instance, this method would add 3-7 frames.

“True” triple buffer V-SYNC, like “alt,” prevents the lock to half the refresh rate, but unlike “alt,” can actually reduce V-SYNC latency when the framerate exceeds the refresh rate. This “true” method is rarely used, and its availability, in part, can depend on the game engine’s API (OpenGL, DirectX, etc).

A form of this “true” method is implemented by the DWM (Desktop Window Manager) for borderless and windowed mode, and by Fast Sync, both of which will be explained in more detail further on.

Suffice to say, even at its worst, G-SYNC beats V-SYNC.



1620 Comments For “G-SYNC 101”

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BlurDawg
Member
BlurDawg

Hello again Jorimt, hope you’re having a great day.

I have a question less related to gsync and more to do with render latency. I’ve noticed as I turn the resolution down, the render latency reduces even at the same fps. In fact I have found that @60fps capped the render latency is around 11.5ms at 1080p compared to 16-18ms latency when capped at 60fps 1440p. At 720p the render latency dropped even further.

As far as I understand, render latency is linked to input latency. Does this mean that for example with console games that are capped at 60fps @4k, the input latency is much higher than it could be if the game was instead rendered at 720p? Since the GPU is doing less work per frame?

AidenJr
Member
AidenJr

Hi, this was exactly what I was looking for, but I still have one unanswered question in my mind.
I’m going to buy a 165hz G-sync monitor, and the game that I play runs around 200 fps. Will I necessarily get screen tear if I don’t cap at 162 ? and do you suggest capping the fps at 162, or playing it on higher graphic settings of the game to stay below the monitor’s refresh rate? like 150 fps or so. Since I play FPS games input lag really matters to me.
Regards

Zole
Member
Zole

After reinstalling windows recently, my G-Sync behaviour has changed.

As far as I can remember, my usual set up was:
League of legends played in Windowed Borderless Mode.
v-sync: disabled – in-game
v-sync: enabled (set to “Fast”) – in NVCP
g-sync: enabled for both windowed and full-screen – in NVCP
preferred refresh rate: Highest available – in NVCP
power management: Prefer maximum performance – in NVCP
Monitor technology: G-SYNC – in NVCP
frame rate: uncapped – in game

With these settings, my frame rate was capped by the fast v-sync to 1 frame below my monitors max refresh rate 164 (down from 165).

However, after reinstalling windows and reapplying these same settings the frame rate is no longer capped to 1 below the monitors refresh rate. Instead I get FPS anywhere from 200-600 and I notice stutters and tearing.

Is there any way for me to get back my previous system behaviour?

PS I know the recommended way to set up a system is for full-screen g-sync but I prefer windowed borderless for the rapid alt tabbing, as I do that frequently.

brdon209
Member
brdon209

I am looking to buy a 1440p 144hz monitor and from what I have read, I should set my FPS at 141 using nvcp, set vsync on in nvcp and off in game. However, many sources have told me to turn on null on and others have told me to completely turn it off. Should I put it on ultra, on or off? I play league of legends fyi and my cpu is usually around 16% usage and my gpu is around 30% uncapped 1080p. Sorry, I am new to th this subject .

georgi74
Member
georgi74

I have a System with a Geforce 3080 and as display I use a LG c9 OLED TV with 120Hz and GSync.

In Nioh 2, which can easily perform over 120 fps with DLSS on 4k with that System if I limit the game to 117 fps with RTSS I get Micro Stutter when just looking around. If I disable the RTSS limiter and let the game limit the fps to 120 (in game there is only an option to lock at 30/60/120) the game is buttery smooth. Is there any way to get the game running smooth with a limit to 117 fps?

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