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.



1090 Comments For “G-SYNC 101”

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tbhee
Member
tbhee

For AMD is it correct to set the framerate limiter through Radeon Chill Min and Max = cap?

And for a game that does have an ingame limiter would it be overkill to be using that as well
as Chill?

Gsyncmasterace
Member
Gsyncmasterace

Hey there 😀

Do you guys know if there is any difference between gsync and a fixed refresh rate with an unlimited framerate ( lets say 400 fps at 240hz ).

Agitatio
Member
Agitatio

Hello again, have another question to bother you with.

So I have 240Hz G-SYNC monitor, and I have G-SYNC and VSYNC enabled in NVCP.
I don’t trust in-game FPS limiters due to too much variance and some games having very weird frame pacing or just bad FPS limiters, which both require too much trial and error.

So considering that, I’m left with limiters like RTSS and NVCP. Which both should be equal by this point when it comes to input lag. So I was wondering if using those kind of limiters is still superior to having VSYNC engage when hitting ceiling, as they can still add up to 1 frame of additional input lag. And I also noticed that input lag difference is not that drastic in some of your comparison graphs for 240Hz with limit and without.

If FPS lock still advisable in my case, do you have a recommended “better safe then sorry / should affect 99.9% of cases” number to lock below refresh rate? Similar to your -3 and ULL overkill of -15(for 240Hz that is)?

vin3780
Member
vin3780

Hi,

I have a NVIDIA GPU and am looking to get a 240hz monitor but it only has Freesync but is G-Sync compatible. So I’m wondering, are the FreeSync monitors with the G-Sync Compatible certifications functionally identical to monitors with native G-Sync modules? Are these tests showing G-Sync and V-Sync ON with capped frames input lag numbers are comparable to V-Sync OFF uncapped frames input lag numbers still applicable to these monitors without native G-Sync?

infraa
Member
infraa

Hello! I got 144 HZ G-sync.

I have a problem when I am playing Rocket League.

Having Vsync NVCP controlled for app and g sync on and in game vsync off, with cap 141 fps, the game goes fine, too smooth!

But if i disable VSYNC from the game, is not smooth anymore, it looks like 60 fps but having 144 fps. If i uncap and it reach to 250 fps is the same, still no smooth.

Its only happens in RL idk why. I tried disabling G-sync and nothing happened.

What could it be?

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