Framerate fluctuates with RTSS limit and GSync.

Talk about NVIDIA G-SYNC, a variable refresh rate (VRR) technology. G-SYNC eliminates stutters, tearing, and reduces input lag. List of G-SYNC Monitors.
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Sintek
Posts: 3
Joined: 16 Jul 2019, 13:17

Framerate fluctuates with RTSS limit and GSync.

Post by Sintek » 24 Mar 2023, 17:14

2560x1440 @ 120hz (119.998)

I've tried numerous limits in RTSS - 116, 117, xxx.998, etc. - but in game (Division 2 mainly) my monitor GUI shows the refresh rate going wild from 110 to 120 which is causing noticeable stutters. Without RTSS, it stays at 120 but then there's increased input lag.

It can't be normal for the refresh to bounce so wildly between and outside of the VRR and FPS limits, right? Is there a way to smooth it out?

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jorimt
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Joined: 04 Nov 2016, 10:44
Location: USA

Re: Framerate fluctuates with RTSS limit and GSync.

Post by jorimt » 24 Mar 2023, 18:13

Sintek wrote:
24 Mar 2023, 17:14
2560x1440 @ 120hz (119.998)

I've tried numerous limits in RTSS - 116, 117, xxx.998, etc. - but in game (Division 2 mainly) my monitor GUI shows the refresh rate going wild from 110 to 120 which is causing noticeable stutters. Without RTSS, it stays at 120 but then there's increased input lag.

It can't be normal for the refresh to bounce so wildly between and outside of the VRR and FPS limits, right? Is there a way to smooth it out?
I've had to address this multiple times over the years in the forums and my article comments section. Most recent answer is below:

vrr-readout-comment.png
vrr-readout-comment.png (159.48 KiB) Viewed 1349 times
Firstly, avoid correlating stutter with the fluctuations seen in the approximated VRR monitor meter. There can be a degree of system-side stutter regardless of G-SYNC or an FPS limit, be it game-side or external.

Secondly, the reason you're not seeing as much stutter without an FPS limit at 120Hz, is because if you're using G-SYNC + V-SYNC, and the framerate is exceeding 120 FPS, it is then reverting to standalone V-SYNC behavior, where, at 120Hz, every frame is throttled to display at 8.3ms per (120 FPS average), but as a result, you get more buffering, which equals more latency (hence the entire point of using G-SYNC with an FPS limit instead).

To be clear, like standalone V-SYNC, G-SYNC prevents tearing, but unlike standalone V-SYNC, G-SYNC is a 1:1 mirror of system performance, including frametime, so if the frametime performance is poor (framerate limiters only ensure a maximum framerate, not a minimum one, so whenever the framerate drops below the RTSS limit, it cannot stabilizing frametimes), G-SYNC will reflect it as-is, whereas standalone V-SYNC (assuming framerates can be consistently sustained above the refresh rate) will not.
(jorimt: /jor-uhm-tee/)
Author: Blur Busters "G-SYNC 101" Series

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