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.



3486 Comments For “G-SYNC 101”

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pacoporrr
Member
pacoporrr

One question, in Windows 11 should we set “Dynamic refresh rate” to “on” (inside ‘System > Display > Advanced display’)?

And also under ‘System > Display > Graphics” the option “Variable refresh rate” should be set to “on”?

Thanks 🙂 nice guide!!

ati
Member
ati

Hello Jorimt,

So I have read through a lot of articles covering this topic. What I am still trying to understand is the following.

Do I achieve lower latency with:

G-Sync + Frame cap in Nvidia Control Panel set manually to 138fps without V-sync (Ultra Low Latency enabled aswell)

or

G-Sync + V-sync and using the Ultra Low Latency mode which automatically caps the FPS in game to 138fps with a 144hz monitor.

Does any of these methods result in lower latency, or are they basically the same. Both seemingly get the job done, but I wonder does using the variant with V-sync maybe cause more lag? Or does the ULL mode which caps it at 138fps basically work like a normal Frame cap mitigating the lag disadvantage of V-sync?

I hope you’re able to follow my questions here. I appreciate your help!

dandyjr
Member
dandyjr

Hey, Jorimt! I hope all is well. I’m writing today because I have a MSI MPG 271QRX QD-OLED monitor on the way and I am curious if you have any experience with using VRR with OLED panels. I am very well aware of the dreaded VRR flicker that everyone talks about but I’m wondering if it’s even worth trying to use VRR with a 360Hz OLED because I know you’ve stated before that the higher the refresh rate, the less necessary VRR becomes. My thought process is that the tearing wouldn’t be noticeable at that refresh rate, but the flickering definitely would be. Have you been able to test VRR on OLED panels and do you think it would be best to just leave VRR disabled on a 360Hz OLED monitor? Thank you so much in advance and thank you for all that you’ve done for the gaming community!

cruxxf
Member
cruxxf

i wonder how the new RTSS reflex mode compares to a manual in-game FPS cap on games that do not support reflex

Treeplex
Member
Treeplex

Hello, I have a BenQ Zowie XL2566K monitor, I play story games and was wondering if I should enable Adaptive-Sync and if I did the right thing by disabling AMA to achieve a cinematic picture?

As for the G-Sync settings in the NVIDIA Control Panel, is it worth setting a frame limiter if my system isn’t even close to achieving 360fps? And which NVIDIA Reflex mode is better to use: “Enabled” or “Boost”?

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