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.



1870 Comments For “G-SYNC 101”

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stadiofriuli
Member
stadiofriuli

I’ve got a question. Got the Dell S2721DGF(A) which is G-Sync compatible, I’m running the monitor at 165Hz.

So what I basically did is to set a FPS cap @161 with RTSS.

Enabled G-Sync fullscreen in NVCP.

Enabled V-Sync in NVCP.

According to the guide V-Sync within the G-Sync range should still act like for native G-Sync monitors when it’s an official supported G-Sync compatible monitor.

What happens for me though is.

When V-Sync is enabled FPS cap at 158, not 161 as set in RTSS.

When I then disable V-Sync and have only G-Sync running it’s capped at 161 again.

So my question really is why this weird behaviour?

Should I activate or deactivate V-Sync in my case?

SvenL
Member
SvenL

Hi,
First of all, thank you so much for creating such an amazing guide. After reading through a few more questions arose.

I’m playing Warzone (FPS game) on a 1080p 144hz free sync monitor with an RTX 2080Ti graphics card. (I achieve 170-180 fps in game uncapped, which is above the refresh rate of my monitor)

My goal is to have a 100% tear-free gaming experience with the least amount of input lag to achieve the best possible accuracy.

First, I took over the following settings from you
NVCP: G-Sync & V-Sync: On

But when it comes to the FPS limiter, I’m still unsure which is best in my case. (Warzone also supports reflex)

In-Game FPS Limiter (141 FPS cap)
Reflex: On / On + Boost
RTSS / NVIDIA’s Max Frame Rate (141 FPS cap)

The question is which of these options has the lowest input lag and at the same time the most constant possible frame time. (I assume these 2 factors are especially important for FPS games)
Or what you think would be the best sweet spot out of all of these options.

With reflex activated (On + Boost), I noticed that the frame rate varies (around 138 fps). I’m not sure whether this will have a negative impact on my frame time or input delay, as I could easily achieve a constant 141 FPS with my graphics card. Should I then prefer the in-game FPS limiter or RTSS / NVIDIA’s Max Frame Rate over reflex?

Thank you very much

RoseGoldCrobat
Member
RoseGoldCrobat

I signed up here since you seem to know a lot about this. I have a very strange issue.

I have a monitor that is Gsync compatible and Gsync is on in fullscreen mode.

When I play certain games, the current ones I’ve seen it in are Red Dead Redemption 2 and Hitman 3 I would like to have gsync on and vsync on. The problem is when both settings are on at the same time my FPS caps to 72 fps, half of my monitor’s refresh rate. I don’t understand why this is happening. Could I be missing a setting?

Zehdah
Member
Zehdah

Hello. I have a new monitor, it’s a Samsung G7 Odyssey which is 1440p 240hz with Gsync. I’m wondering what you would recommend for optimal performance/gaming with that setup since it’s unlikely I will hit 240hz in a game at 1440p with a 1080ti, should I still follow the above instructions and cap to 237 along with vsync on in CP, off in game? Curious if there’s any extra things I need to do.

RealRomen
Member
RealRomen

Hello, im using Gsync + Vsync (NVCP), i was wondering if i should enable triple buffering, i heard it improves stability because my frametimes are really inconsistent in one of my games

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