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.



594 Comments For “G-SYNC 101”

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hobbitwho
Member
hobbitwho

If my cpu is the bottleneck (in some games it is sadly) should i still follow this guide? (i’ve a 240hz, i set the frame limit to 237 in the game that caps my CPU and i’ve set low latency to “on” (1 pre-rendered frame)
i5 8600k @4.8ghz
RTX 2070

CrystalUnclear
Member
CrystalUnclear

How did you get NVCP V-sync to work in Windowed/Borderless modes? I’m on Windows 7 and I’ve tried disabling Aero, and it still can’t be forced.

BlackStorm82
Member
BlackStorm82

Hello. Sorry for frequently asking questions
Low Latency Mode Ultra
Is prerendering “0” correct?

G-Sync + V-Sync + Low Latency Mode Ultra
Is prerendering limiting the frame to “0”?

On this site
Gsync + V-Sync + Low latency Mode Ultra
Is it correct to add a frame limit to pre-rendering “1”?

If so, is it correct to write Gsync + V-sync off + Low latency mode Ultra to use pre-rendering as “0”?

Zehdah
Member
Zehdah

If I get a 240 Hz monitor, like the BenQ ZOWIE XL2546, should I still be using the method above (Gsync on, Vsync off in game, on in control panel and cap FPS to 237 with RTSS) or should I uncap my framerate with Vsync and Gsync off? The reason I ask is a lot of pros in FPS games such as Apex, Siege, CSGO, seem to do the latter and I can’t understand why, unless G-sync isn’t available on those monitors, but I read that G-sync is available on freesync monitor’s now with 10xx and above cards, am I wrong? Greatly appreciate any input!

DanWensing
Member
DanWensing

Which one has the lowest input lag?
1. Gsync + Vsync + Low Latency Mode at Ultra (no fps limit)
2. Gsync + Vsync + NVC/RTSS fps limit (3fps below Refresh rate)

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