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.



273 Comments For “G-SYNC 101”

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Sort by:   newest | oldest | most liked
Phroster
Member
Phroster

Why is it, that in most games, borderless fullscreen + gsync, gives worse results then exclusive full screen mode? (uneven frametimes, micro stutters)
Using a frame limiter to set the framerate -3 below the refresh rate makes it even worse when using borderless fullscreen.

I did find that G-sync + Fast sync + borderless fullscreen seems to give better results in some games. Still limiting the frame rate in borderless fullscreen, introduces microstutters.

Why is borderless fullscreen so unreliable with gsync enabled?

jdawg
Member
jdawg

Hey, so I didn’t know about turning on V-sync in NVCP only, but before I did that I was getting the occasional stutter even though the action on screen wasn’t that intense. I have RTSS showing a graph of FPS and I notice there are several little dips happening every second. The game moves smooth but then I get the stutter occasionally. I’ve closed everything unnecessary but maybe there’s more to close…not sure what other processes I can close in Windows 10 and I haven’t done any optimizations like in Windows 7.

Fast forward to setting it up as recommended here (141 FPS limit in game for my 144Hz monitor, G-sync on, V-sync ON in NVCP only, V-sync OFF in-game) and I noticed that the dips on the graph are even deeper…however I haven’t seen a stutter yet and the game plays very smooth with no lag. Any explanation for those dips in the graph though?

metalpizza123
Member
metalpizza123

Hi hi, Just a quick heads up for users with several displays of varying refresh rates. Windows will sometimes only report the lowest refresh rate monitor as the system-wide V-Sync target. After testing on driver ver 436.02, with 3 different monitors, here are my findings. I testeed with 3 games, all had similar behaviour. I used the recommended settings as per the guide.
NVCP V-sync ON
Gsync Enabled
Ingame FPS Limiter or RTSS used
Ingame Vsync/buffering disabled

Main monitor :G-Sync, 144hz.
Second Monitor 60 Hz
In game Framerate 60~

Main monitor :G-Sync, 144hz
Second monitor 75 Hz
In game Framerate 75~

Main monitor G-sync,144hz
Second monitor, 60hz
third monitor, 75hz
In game framerate 60~

Only main monitor: G-Sync 144hz
In game frame rate 140~

There’s probably a way to disable this, but for now I’ve resorted to just unplugging my other monitors. Just a note for any multi monitor users. I wish I could test more, but I just wanna play games.

kucki
Member
kucki

Should we use the “Low Latency Mode” On or Ultra with G-Sync?

Chief Blur Buster
Admin

Possibly beneficial for uncapped GSYNC + VSYNC ON. Will need to be tested.

This will reduce lag differential of below-Hz (GSYNC behavior) versus match-Hz (VSYNC ON behavior).

Creakffm
Member
Creakffm

Hello Guys, really Intresting Article/Guide but i wanna know something from you.

i Playing Games since 20 Years i know in Old Times with 60 HZ Monitors i play Competitive Games with VSYNC off to get most FPS ingame.

So back to 2019.

Im Using a Nvidia Geforce 1080 TI and my Monitor is 240 HZ DELL Alienware AW2518HF with GSYNC on Displayport Cable.

i wanna Optimizing all to Play Competitive. Actual i play with Ingame Fortnite Framerate Limit 240 HZ because see this by a lot of People.

When i wanna get less Inputlag i set in Nvidia Inspector Framerate Limiter to 245,244 ( more FPS than HZ or less and than which one is best? )

thanks for Answering

wpDiscuz