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.



90 Comments For “G-SYNC 101”

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pervyjutsu
Member
pervyjutsu

Should “Reduce Buffering” option in Overwatch be enabled or disabled? Many competitive/pro players suggest having reduce buffering on to get higher framerate and reduced input lag but would having this option on have a negative effect on G-SYNC?

Also I recently upgraded my system to a i7-8700k and 1080ti. I usually sit at a steady 300fps on Overwatch now and use a 240hz monitor (Asus PG258Q). Would G-SYNC be worth using in this case?

shashank066
Member
shashank066

Excellent article. Just like other on Blur Busters. It was such detailed that, I had to read it twice to understand perfectly. Thanks for this.

bcbuse
Member
bcbuse

First, this is the best Gsync/Vsync information on the internet. I appreciate the effort you put into this, well done.

I read a comment you posted somewhere that ‘technically’ the absolute least input lag would be with Gsync Off + Vsync Off + Framerate upcapped(getting at least 2x the monitor refresh rate). Can you approximate how much less input lag that would be versus Gsync On + Vsync On(NVCP) + Framerate capped 2 below monitor refresh rate?

daniel8747
Member
daniel8747

to clarify: with fps capped 2-3 fps below monitor refresh rate, do i still need to have v-sync enabled?

Abiak
Member
Abiak
jorimt please answer. 1) NVIDIA Control Panel G-Sync: Full Screen vs. Windowed and Full Screen, which one should I use for gaming? 2) Does just “full screen” work on windowed borderless? 3) Preferred refresh rate “Highest Available” or “Application controlled”? 4) Does “Highest Available” work on windowed borderless? 5) From what I understood, for a 144Hz monitor, the best options are gync + vsync on (NVCP) + in-game vsync off and frame limited to 142 fps. However I don’t get why you need vsync, why gsync + frame limiter is not enough? 6) If the game has no fps-limiter, you… Read more »
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