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.

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.

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:

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



172 Comments For “G-SYNC 101”

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Member
king37

Very helpful

Member
besweeet

To confirm, G-SYNC ON + v-sync ON is better than G-SYNC OFF + v-sync ON? My ultimate goal is to eliminate tearing while not introducing input lag, so it seems like the former is the way to go.

Member
hkeep

Thank you for those detailed explanations. My question is why would we enable v-sync if it would never reach the refresh rate cap with the rtss. And also, if for example, I am consistently running the game at a higher refresh rate than my monitor (which is 120hz), what is the point of rtss if it would limit my fps to 2-3 frames below the refresh rate? Shouldn’t I just enable G-sync without a limit which as you said has less input lag than v-sync even when the fps goes over the refresh rate. Which brings to the question of why do we need v-sync at all?

Member
Dragonite

I have the Viewsonic VX2458-C-mhd which is a Freesync monitor. Since my GPU is GTX 1080 i could enable G-sync with the latest drivers. But the problem is that i have brightness flickering (which i read that is a quite frequent occurrence to all adaptive sync technologies). Since i tried to fix it but nothing worked i disabled Freesync/G-sync. So the question is, now that G-sync is off, should i just enable V-sync (NCP) + framelimit for better visual quality and prevent tearing or leave V-sync (NCP) off but still use framelimit?

Member
hyrnos

Hi, thanks for the excellent guide

I want to play games that are capped to 60 ish fps by their game engine, should i enable vsync? (assassin’s creed) I ofc want to enable gsync

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