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.



1456 Comments For “G-SYNC 101”

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Talos-LXIX
Member
Talos-LXIX

Hello there!
First i just want to say thank you so much for all the amazing work you guys do. in-depth analysis and guides like this are really helpful.

I just have a few things that I’m not entirely sure about.

1) You’ve found that G-SYNC completely bypasses the 1 frame of delay add by DWM in windowed/borderless. is that only the case if you’re within the G-SYNC range with V-SYNC enabled? could you still bypass it if you ran G-SYNC with V-SYNC off while being over your monitors refresh rate?

2) is G-SYNC+ V-SYNC off with fps over the monitors refresh rate identical to G-SYNC off + V-SYNC off?
For some reason some games (Apex Legends for example) lock their fps to my monitors refresh rate (120) when i try to disable G-SYNC via the per program settings on the NVCP.
I typically like to disable it for competitive FPS games as i can get much higher FPS than 120.

Hiram
Member
Hiram

Hello, I have read a lot, but I have a question.
In my case I play Fortnite, and if I limit the fps to 144 in the game and in the NVCP the screen tearing is not very noticeable, but it happens, otherwise if I play at limited 120 fps the screen tearing is much more noticeable, ( also putting 120hz in the NVCP).
Of course, my fps are not very stable when I get into a fight, they drop from 120 to 100 or a little less.
My question is, do I have to have V-sync activated?
I hope you can answer me

ZaDDy StEvO
Member
ZaDDy StEvO

For the best system latency performance using GSYNC for no screen tears with Reflex, should the setup be GSYNC + VSYNC + Reflex + No FPS Cap, or add an FPS Cap under what Reflex auto caps under monitors refresh rate?

IAm2Epic4This
Member
IAm2Epic4This

Is this advice for specific programs using the “Program Settings” or for the entire system using the “Global Settings” tab of the NVCP? Is there a downside to setting this up using the optimal g-sync settings section system wide? Sorry if it is a dumb question but I don’t know if it has any impact one way or the other and it wasn’t clear to me. Appreciate the guide, it is really helpful!

CG2X
Member
CG2X

Say I have a 144hz GSYNC monitor, gsync and vsync are enabled in nvcp, and I can only reach 80 fps consistently in this game, should I set the maximum fps to 141 or to 80 to get the best tear-free experience with minimum input lag?

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