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.



3099 Comments For “G-SYNC 101”

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dandyjr
Member
dandyjr

Hello there! I recently bought a 500Hz G-sync monitor and it’s the first time I’ve owned a true G-sync monitor with a module. The exact model is the AW2524H. One of the first things I noticed with this monitor is that the frames never hit the max range of the monitor as if the module has it’s own way to prevent leaving the G-Sync range. The monitor is technically a 480Hz panel but it has a factory overclock you can set to 500Hz. In stock form (with all of the proper G-sync settings in the control panel) the frames automatically are capped at 477 and never will hit 480. Overclocked to 500Hz, The frames will never go above 496. I tested multiple games just to make sure and they all produced the same results. What I’m wondering is if this is an effect of this specific model or if this is true for all G-Sync native monitors. Does this mean that I never have to cap my fps because the monitor won’t allow the frames to hit the ceiling anyway? I noticed that if I enable reflex in supported games, the frames will be capped at 438 instead of 496. My guess is that Nvidia set such a low limit to be safe for G-Sync compatible monitors that happen to be 500Hz (since I’ve heard they are less accurate and will leave range more often). What are your thoughts on this? I’d be stoked to hear that I don’t have to cap my fps anymore but it seems too good to be true haha!

IggyRex
Member
IggyRex

Hello, you probably get asked this a lot, but I game on a lg c1 at 120hz, and I was wondering what would be best for my setup. I am currently using Vsync – on in the control panel, but I am unsure if I should set low latency to ultra or if setting to On would be the better option for me. Having it set to ON would require me to set an fps limit on a game basis correct? So something like elden ring would work better being capped to 59 or 57fps as opposed to it set to ultra which would do it for me. What are the benefits of either option? Sorry, and please let me know. I just want to get the most out of my hardware and out of gsync.

Kaffik
Member
Kaffik

Hi!
I have 165 Hz G-Sync Compatible (ls27ag500nuxen) monitor.
I used all your tips for this type of display but something irritates me a lot.
60 fps on my screen looks like 30-35 at best, I need to have like 95-100 fps to make it look like smooth 60.
For example my boyfriend has 144 Hz VRR TV and 60 fps looks like 60 fps.
I have DP 1.4 and VRR on.
Do I really need a G-Sync module to make it better?

Indignified
Member
Indignified

Hello, is there any point of having gsync or reflex on if fps is uncapped?

ChillyWilly219
Member
ChillyWilly219

Hello, on my LG Ultragear OLED 45GR95QE-B monitor I have experienced flickering in games like Lords of the Fallen or Hellbalde, even in Warzone. A slight flicker mainly in the menus and loading areas. Is there a solution to this problem? Many people say to turn off g sync directly. What do you recommend me?. Greetings.

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