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.



2042 Comments For “G-SYNC 101”

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zikalol
Member
zikalol

Hi, i have a dell freesync monitor. The issue is when i enable Gsync the monitor turns off mid-game. can’t figure out what is causing this issue. thank you

Zanity
Member
Zanity

Hi, quick question, why do we still need to set 3 fps lower if we use nvidia ultra low latency mode ? which automatically force caps the frame rate lower already. thanks

Zehdah
Member
Zehdah

Hi Jorimt. I’m just wondering if the “variable refresh rate” option in Windows 10 graphics settings should be enabled or disabled or if it makes no difference? I use a Gsync monitor.

domfak
Member
domfak

Hello,

Want to thank you for all the info in this page.
Also I have couple of questions:

I got RTX 3080 + 165hz monitor, I am having those tearing lines on my low side of display if I play with GSync + uncapped fps. Sometimes it feels like stuttering. So I decided to try your method.
But where are some issues in game COD: Warzone:

1) GSync On + Vsync ON + LLM (Ultra) + Reflex On + Boost – caps my FPS in game at 60. Why?

2) GSync On + Vsync FAST + LLM Ultra + Reflex On+ Boost – I can cap myself at 161fps as you proposed. And FPS are dipping from 140 to 161. Also with thise method I found that blur line in the bottom of the screen still exist.

What is difference between VSync ON / VSync Fast?
Will I get more input delay in this case?
Also can I feel that option with Gsync + Vsync has more input delay on my mouse or it is only placebo?

Thanks for an answer.

majkool
Member
majkool

1. So with 390Hz monitor input lag with GSYNC + VSYNC and 386fps game limitter is nearly the same like with GSYNC/VSYNC off and fps_max 0 in CSGO.
2. I know that with 240Hz monitor there is a few ms delay with these options but I think it’s still better to accustom to it and play on a pro level?

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