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.



347 Comments For “G-SYNC 101”

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dotyerts
Member
dotyerts

I’ve been reading your stuff for years. Appreciate all of it.
Let me get this summarized in one quick writeup.

I have a freesync compatible monitor viotek gft27db 144hz. If i enable G-SYNC properly with my DP cable on an RTX 2070, and have VSYNC ON, as well as + NULL, then I should
1. be all good in terms of enabling GSYNCwithout the issues of VSYNC off causing tearing sometimes.
2. NOT be required to Limit my fps to 141 by using RTSS? I’m currently using it limited to 141 to stay under and avoid the buffer flip interval.
2.b. wondering if this is the case, so I can turn off RTSS and retrieve that minuscule amount of input lag it causes.

nuk_won
Member
nuk_won

Tell me if I am wrong. But I think I figured it out. G-sync it self don’t ad input lag so if i have it I might as well turn it on to get stutter/screen tearing free game play. So as I understand u turn g-sync on + vsync off find the fps by caping it 165 then 164 ect where there is no screen tearing at bottom of the screen let’s say it would be 158 then u go Nvidia control panel turn g-sync on vsync off set low latency to ultra and cap ur fps at 158 and this is the way u get lowest input lag + as it would be running a monitor who don’t have g-sync and just caping fps at 165fps but this way u don’t get the benefits as smooth game play no stuttering. This would be best only for GPU bound games like apex legends other games that use CPU this could increase input lag? Please correct me if I’m wrong or maybe I need to turn g-sync off set fixed refresh rate null set to ultra fps cap at 165. Main game is apex legends. This I how I run the game currently.

Specs pc: 87k at 4.5gh 1080ti oc. Monitor: AOC 24″ 2k rez 165hz g-sync.

Ownsin
Member
Ownsin

Hey there. Can I ask If I should turn on V-Sync in-game or from the Nivida Control Panel for my G-Sync 144hz monitor? I recently watched a video for Battlenonesene where he says turning on V-Sync inside of games is better than turning it on from the NVCP because some engines have optimizations for their V-Sync. What’s your take on this matter?

Another thing I want to bring up. Can you tell me what’s the difference between turning on V-Sync and Fastsync from the NVCP? as far as I know, Fastsync eliminates tearing, leaves the frame rate unlocked and doesn’t add nearly as much input lag as regular V-Sync, so why is it recommended that we use V-Sync instead of Fastsync?

P.S: which frame limiter do you suggest I should use.

Thank you.

gzmm
Member
gzmm

Hello, i have a samsung C24FG73, with 70~144hz freesync range.
for me, gsync+vsync in driver with 138 fps limiter seens to be working very well.
but, if a game is locked at 60 frames, the gsync will be ‘disable’, and only vsync will work, correct?
this will introduce alot of input lag, or the FLC helps?

buddersnaps
Member
buddersnaps

Hi when running a game that GPU is using 100% resources do i still want NVCP v sync set ON and low latency set to Ultra. i have g sync monitor thats 144hz. i have games capped at 141 but get about 100 – 120 most of the time. are my settings still correct when getting frames below monitor refresh rate and GPU bound using NVCP v sync ON, low latency ULTRA, Gsync ON, and in game fps capped to 141 and vsync off?

then to clarify when not gpu bound just use the “on” option instead of ultra for low latency?

also monitor has ULMB or should i just stick with gsync? if i used ULMB what would i do for vsync and latency options?

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