G-SYNC 101: External FPS Limiter HOWTO


In-game vs. External Framerate Limiters

As described in G-SYNC 101: In-game vs. External FPS Limiters, In-game framerate limiters, being at the game’s engine-level, are almost always free of additional latency, as they can regulate frames at the source. External framerate limiters, on the other hand, must intercept frames further down the rendering chain, which can result in delayed frame delivery and additional input lag; how much depends on the limiter and its implementation.

In-game framerate limiters, however, aren’t available in every game, and while they aren’t required for games where the framerate can’t meet or exceed the maximum refresh rate, if the system can sustain the framerate above the refresh rate, and a said option isn’t present, an external framerate limiter must be used with G-SYNC to prevent V-SYNC-level input lag instead.

RTSS is a CPU-level FPS limiter, and introduces up to 1 frame of delay, whereas Nvidia Inspector uses a driver-level FPS limiter, which introduces 2 or more frames of delay. See G-SYNC 101: In-game vs. External FPS Limiters for complete details, along with input latency tests comparing the two external solutions against an in-game limiter.

RivaTuner Statistic Server: <1 Frame Delay

RTSS is available standalone here, or bundled with MSI Afterburner here.

If only a framerate limiter is required, the standalone download will suffice. MSI Afterburner itself is an excellent overclocking tool that can be used in conjunction with RTSS to inject an in-game overlay with multiple customizable performance readouts.

Blur Buster's G-SYNC 101: External FPS Limiter HOWTO

RTSS can limit the framerate either globally or per profile. To add a profile, click the “Add” button in the lower left corner of the RTSS windows and navigate to the exe. To set a frame limit, click the “Framerate limit” box and input a number.

Nvidia Inspector: 2> Frame Delay

An unofficial extension of the official Nvidia Control Panel, Nvidia Inspector (download here) exposes many useful options the official control panel does not, including a driver-level framerate limiter.

Nvidia Inspector can limit the framerate either globally or per profile (more details on profile creation can be found here).

To set a frame limit, locate the “Frame Rate Limiter” dropdown in the “2 – Sync and Refresh” section, select the desired limit, and then click the “Apply Changes” button in the upper right corner of the Nvidia Inspector window.

Blur Buster's G-SYNC 101: External FPS Limiter HOWTO

As of Nvidia Profile Inspector version 2.1.3.6 and Nvidia driver branch R381 or later, a new “Frame Rate Limiter Mode” dropdown has been introduced with a “Limiter V2 – Force Off” option:

Blur Buster's G-SYNC 101: External FPS Limiter HOWTO

This option claims to reduce the limiter’s input lag; exactly by how much, and with what combination of settings, remains to be determined.



1152 Comments For “G-SYNC 101”

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AlianosFN
Member
AlianosFN

Hi, I have a question.

I play Fortnite competitively on a 165 Hz 1440p monitor with a GTX 1070 Ti using pretty much all the settings you recommended in this thread (gsync ON, vsync ON, game on fullscreen, fps limited in game files to 162, and finally low latency mode ON).

Now since the nvidia driver update from today got released the new nvidia Reflex Low Latency setting was added to the game. With the setting come 3 options: OFF, ON or ON + BOOST. A thing i noticed when i turned it to either ON or ON + BOOST was that instead of my fps cap being 162, my fps got capped at 158 (so 4 frames lower than the limit i set myself).

This raised a question;
Does turning the setting ON (or ON + BOOST) impact the way gsync works (also in combination with the other recommended settings in this thread)?
If so, what would you recommend me to do? Should i keep the nvidia reflex setting off? Or should i keep it on (since according to nvidia it reduces system delay) and change my fps cap to make up for the 4 frames i lost?

Ultimately i think my question is; how does the nvidia reflex low latency setting fit in the picture with gsync and the recommended settings in this thread?

Thanks in advance for taking the time to read/answer to my questions!

tomato884
Member
tomato884

does this apply to the new 30xx series with all the new reflex technology?

JediBrysen
Member
JediBrysen

should competitive players for any game but for my situation fortnite use this? I really just want low input delay while it being smooth

ankurszn
Member
ankurszn

i have the same question

Avean
Member
Avean

Could LLM = On with G-Sync cause frametime spikes in cases where the game uses its own frame queue? Cause in the end of the article you say you recommend testing this on per-game basis to see if worse or not. And if at best youre improving latency by 1 frame, its kinda best to leave it off i feel? Unless you want to fire up RivaTuner and monitor each game to see if improvements. But really the biggest impact is more framerate than whatever setting your LLM is at, feel people are kinda hung up on this setting 🙂

Glarbstintenford
Member
Glarbstintenford

Amazing guide and information, thank you so much!

I have a questions or two, sorry this ends up being so long but I wanted to also share the information I found and make it as clear as possible:

1 – Does the use of the smoothframes feature found in Unreal Engine 4 have any effect? I’m not sure how smoothframes & in game Vsync relate to each other with or without G-Sync and thought you could shed some light.

The game I play is online multiplayer only, and their servers currently run 30Hz tickrate, which in the near future will be increasing to 60Hz tickrate.

It has smoothframes and vsync enabled by default, using the default 22-62FPS range for smoothframes, with no in-game option to disable either or set an FPS limit. It also has what I am assuming is an in-game FPS limiter that you can manually adjust via editing the ini files. This line is FrameRateLimit= and the default is =0.000000.

Also just so you know this game has no in-game settings other than a resolution scale slider that’s it, and only runs in borderless fullscreen.

However you can edit GameUserSettings.ini and disable/enable vsync & smoothframes.

Now with or without G-Sync enabled I have discovered the following:

– If I use the games default settings of vsync and smoothframes enabled and FrameRateLimit=0 I am limited to 62FPS regardless of desktop refresh rate provided that my desktop refresh rate is higher than 63Hz **However if I set FrameRateLimit to any number up to and including 120 then my FPS limited to that number unless my desktop refreshrate is lower than the value set in FrameRateLimit= in which case it is limited to desktop refresh rate.

– If I disable in-game vsync and leave smoothframes enabled I am still limited to 62FPS regardless of desktop refresh rate if FrameRateLimit=0

– If I keep in-game vsync enabled and only disable smoothframes my FPS is capped to desktop refresh rate but only to 120 any refresh rate above that I’m still limited to 120FPS. Also worth noting this is when leaving FrameLimit=0.000000

– If I disable in-game vsync & disable smoothframes and FrameRateLimit=0 then my FPS is uncapped.

Wonderinig if smoothframes should be enabled or disabled, as well as if using FrameRateLimit should be used and am curious what your thoughts are about it all.

Thank you! 🙂

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