G-SYNC 101: G-SYNC vs. V-SYNC OFF


Beyond the Limits of the Scanout

It’s already been established that single, tear-free frame delivery is limited by the scanout, and V-SYNC OFF can defeat it by allowing more than one frame scan per scanout. That said, how much of an input lag advantage can be had over G-SYNC, and how high must the framerate be sustained above the refresh rate to diminish tearing artifacts and justify the difference?

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

Quite high. Counting first on-screen reactions, V-SYNC OFF already has a slight input lag advantage (up to a 1/2 frame) over G-SYNC at the same framerate, especially the lower the refresh rate, but it actually takes a considerable increase in framerate above the given refresh rate to widen the gap to significant levels. And while the reductions may look significant in bar chart form, even with framerates in excess of 3x the refresh rate, and when measured at middle screen (crosshair-level) only, V-SYNC OFF actually has a limited advantage over G-SYNC in practice, and most of it is in areas that one could argue, for the average player, are comparatively useless when something such as a viewmodel’s wrist is updated 1-3ms faster with V-SYNC OFF.

This is where the refresh rate/sustained framerate ratio factors in:

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

As shown in the above diagrams, the true advantage comes when V-SYNC OFF can allow not just two, but multiple frame scans in a single scanout. Unlike syncing solutions, with V-SYNC OFF, the frametime is not paced to the scanout, and a frame will begin scanning in as soon as it’s rendered, regardless whether the previous frame scan is still in progress. At 144Hz with 1000 FPS, for instance, this means with a sustained frametime of 1ms, the display updates nearly 7 times in a single scanout.

In fact, at 240Hz, first on-screen reactions became so fast at 1000 FPS and 0 FPS, that the inherit delay in my mouse and display became the bottleneck for minimum measurements.

So, for competitive players, V-SYNC OFF still reigns supreme in the input lag realm, especially if sustained framerates can exceed the refresh rate by 5x or more. However, while at higher refresh rates, visible tearing artifacts are all but eliminated at these ratios, it can instead manifest as microstutter, and thus, even at its best, V-SYNC OFF still can’t match the consistency of G-SYNC frame delivery.



2981 Comments For “G-SYNC 101”

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wrdh
Member
wrdh

Hey! I hope you can help me. My PC setup includes an RTX 4070 (ASUS TUF OC), i5-14600KF, and an ASUS TUF VG27AQA1A monitor (supports FreeSync and is G-Sync compatible). My problem is that games don’t feel smooth, even though the FPS shows 144-170 (currently using DisplayPort, 165Hz), with FreeSync turned on and G-Sync for fullscreen games also turned on. When I use G-Sync, my monitor flickers (only in fullscreen games).

Here’s a summary of the settings:

V-Sync is on
LLM – Ultra
G-Sync is on
I’ve had this problem since I bought my new PC a month ago. I don’t think games should look like this, so I suspect a driver update might help when a new version comes out.

Thank you for your time!

kizx
Member
kizx

hey πŸ˜€ , quick question was gives the less latency between RTTS to cap frame or NVCP? thanks

jtcuth48
Member
jtcuth48

Hey Jorimt! Apologies if this has been asked before.

If the game does not have customizable vsync settings and it’s forced on (mainly looking at the From Software games here), is enabling vsync in the control panel still optimal? Will in-game vsync on and the control panel vsync conflict and create any adverse effects? Should I let the 3D application decide in this case?

Thanks!

kizx
Member
kizx

Hello Jorimt, I have a question for the longest time I have like weird feels bad/ stuttering /frame drops idk how to call it in my league of legends game due to dual monitor my primary being 140 hz and my secondary being not the same 60 hz. After reading your post about imput-lag I managed to isolate to problem by going full screen with G-sync-V-sync on in the nvidia control panel but then I keep reading you also mention that if the game we are playing doesnt allow to set a custom value for fps we must do it with RTTS or insane nvidia so I did 141 inside Nvidia. My question is do I need to change it to 141 even if I have the V-Sync on from nvidia or not? But then I kept on reading and also tried the low latency mode on and ultra. From my testing ( very hard to tell the difference ) I think ON gives me the lowest latency and I think ultra gives me the best Hz, frames stability of every animations but overall I do feel like I have more latency having V-sync then not having it. capping my fps at 141 in Nvidia control panel with G-Sync and low latency ultra or ON do seem to feel like im at lower latency with no tearing but its not as perfect than if I had V-Sync on…

What should I do to have the best of both worlds : low latency feeling smooth but also no hz monitor/frames issues.

Thank you.

finaltidus
Member
finaltidus

Hi Jorimt! Glad to see that you are still active here. Sorry I have some very noob questions on my recent weird observations on certain games which I play.

I have recently upgraded my monitor and graphics card to a G-Sync compatible 4k 144hz Dell G3223Q and RTX 4070. My CPU is i5-8600K so I understand that I may experience moderate to severe CPU bottlenecking. On the latest Nvdia 551.52 driver.

My current settings on NVCP are as follows with my target as having the lowest input lag following your optimal settings article.

G-Sync – ON
V-Sync – On
LLM – Ultra

All of my games stay way below the 144fps threshold without any fps limiter. The G-sync range for this monitor is 48-144hz.

Recently I play this game Robocop- Rogue City. There is no Reflex support on this game. With the above settings, my fps is around 60-70fps but with MAJOR stutters until it’s almost unplayable. It cannot be my CPU bottleneck as the CPU is around 40% utilisation. My GPU also ranges from 80-90% utilisation.

I was trying frantically to try to resolve this stutter problem but to no avail. Then for the fun of it, I just set LLM to off and tried out the game. Guess what? No stutters and GPU utlisation went to 99% most of the time. My FPS went to around 80-90fps and very smooth!

I tried to set LLM to Ultra and Off again to ensure that this wasn’t a one off event. But no. LLM Ultra=stutterfest while Off=smooth

Any reason why this is happening? Should I then set LLM as Off for my case in all games going forward for games that DO NOT support Reflex?

In my other games that have Reflex, I set it as On+Boost as default and so far no problems with it.

I understand that Reflex will override LLM regardless of the setting in NVCP.

What then should be the optimal settings in my current specs and objective in achieving lowest input lag, tear free experience and minimal stutter? I am not keen on trying every single game I have and having to tinker with the settings all the time as I have 100+ games on my PC so I would appreciate a general guide to an optimal settings.

Thank you so much!!! πŸ™‚

Thxt
Member
Thxt

Turn LLM on “ON” or “OFF”. You can find it https://blurbusters.com/gsync/gsync101-input-lag-tests-and-settings/8/. I think in ur case you want to set LMM to “ON”, just check the link i sent for jorimt’s answer.

finaltidus
Member
finaltidus

Thanks!!

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