G-SYNC 101: G-SYNC Ceiling vs. FPS Limit


How Low Should You Go?

Blur Busters was the world’s first site to test G-SYNC in Preview of NVIDIA G-SYNC, Part #1 (Fluidity) using an ASUS VG248QE pre-installed with a G-SYNC upgrade kit. At the time, the consensus was limiting the fps from 135 to 138 at 144Hz was enough to avoid V-SYNC-level input lag.

However, much has changed since the first G-SYNC upgrade kit was released; the Minimum Refresh Range wasn’t in place, the V-SYNC toggle had yet to be exposed, G-SYNC did not support borderless or windowed mode, and there was even a small performance penalty on the Kepler architecture at the time (Maxwell and later corrected this).

My own testing in my Blur Busters Forum thread found that just 2 FPS below the refresh rate was enough to avoid the G-SYNC ceiling. However, now armed with improved testing methods and equipment, is this still the case, and does the required FPS limit change depending on the refresh rate?

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

As the results show, just 2 FPS below the refresh rate is indeed still enough to avoid the G-SYNC ceiling and prevent V-SYNC-level input lag, and this number does not change, regardless of the maximum refresh rate in use.

To leave no stone unturned, an “at” FPS, -1 FPS, -2 FPS, and finally -10 FPS limit was tested to prove that even far below -2 FPS, no real improvements can be had. In fact, limiting the FPS lower than needed can actually slightly increase input lag, especially at lower refresh rates, since frametimes quickly become higher, and thus frame delivery becomes slower due to the decrease in sustained framerates.

As for the “perfect” number, going by the results, and taking into consideration variances in accuracy from FPS limiter to FPS limiter, along with differences in performance from system to system, a -3 FPS limit is the safest bet, and is my new recommendation. A lower FPS limit, at least for the purpose of avoiding the G-SYNC ceiling, will simply rob frames.



2975 Comments For “G-SYNC 101”

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Sort by:   newest | oldest | most liked
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!!

ChemicalCthulhu
Member
ChemicalCthulhu

Hey jorimt! Thanks for the awesome and in-depth guide, I just had a few questions for clarification…

1. If the game has an FPS limiter that maxes out at 120fps, and I have a 165hz Monitor with the correct Gsync Settings (-3 from refresh rate, vsync on in NVCP, etc), do I turn off the frame limit in NVCP? Or do I leave it on? Are there any other settings I add to this?

2. If I’m playing a game that I can’t reach my max FPS on (162FPS in this case), do I set my FPS to the limit it can hold via NVCP but still follow the -3 minimum rule? (So for example, if I can only reach 100FPS do I set my limit to 97FPS?)

3. Is there any way to minimize screen flickering when using GSYNC or is this just something I have to contend with? For reference, I am using an MSI G273 Monitor that falls under the “Gsync Compatible” category, and the flickering is mainly on loading screens.

Thanks again, jorimt. I look forward to your response!

crazyhelmet
Member
crazyhelmet

Nvidia launched a new driver saying Ultra Low Latency Mode now work with directx 12 titles, what does that change with this guide?

wpDiscuz