Variable refresh rate

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Variable refresh rate (VRR), also referred to as adaptive sync, allows the monitor to adjust its refresh rate to the output signal. This allows for games to eliminate screen tearing with less of the usual downsides of Vsync (such as stuttering). For a comprehensive look at VRR see PC Gaming Wiki.

Overview

There are multiple implementations of VRR:

FreeSync is AMD's implementation of VESA's VRR standard, and the phrases are often used interchangeably. FreeSync branded monitors should be compatible with all VESA compatible drivers.

Gsync is NVIDIA's proprietary hardware and software implementation of VRR.

Intel plans on implementing VESA's standard in their upcoming 11th Gen and dedicated GPUs. [1]

VRR compatibility and implementations

Driver	VESA	Gsync
AMDGPU	FreeSync	No
Intel	Planned	No
Nouveau	Not Supported	Not Supported
NVIDIA	Gsync Compatible	Gsync

Note: Nvidia GPUs older than their 10 series do not support "Gsync Compatible" monitors.

Xorg configuration

Enable on AMDGPU

FreeSync is only available if your monitor is compatible with FreeSync, as well as if your GPU is compatible with FreeSync.

If you are using a laptop, you can check if your laptop is compatible with FreeSync.

Using an Xorg conf file

Add the line to your AMDGPU .conf file in the Section "Device" block:

Option "VariableRefresh" "true"

Verify vrr_capable is set to 1 using xrandr:

$ xrandr --props

vrr_capable: 1
        range: (0, 1)

xrandr will show the properties for all video output ports; make sure to look at the one that's actually connected to your monitor - the other outputs will report vrr_capable: 0.

Enable on NVIDIA

Using a Xorg conf file

This article or section needs expansion.

Reason: This section needs info. (Discuss in Talk:Variable refresh rate)

Via nvidia-settings

Gsync monitors should automatically be enabled. To enable Gsync compatible monitors do the following:

In nvidia-settings go to the "X Server Display Configuration" page, then under the Advanced button is the option to "Allow G-SYNC on monitor not validated as G-SYNC Compatible". Then click apply.
Now, under OpenGL settings, check "Allow Gsync/Gsync Compatible."

Tip: In the same menu, you can check the "show Gsync indicator" option to display an indicator that Gsync is working in the top right corner.

Wayland configuration

KDE Wayland should automatically enable VRR for full screen applications [2].

Sway

Sway supports variable refresh rate as of version 1.5. To enable it for all of your outputs you can add the following to the sway config, or apply the setting to on a per output basis:

output * adaptive_sync on

You can verify that your display supports adaptive sync with swaymsg:

$ swaymsg -t get_outputs

Output DP-1 'Display Name'
  Adaptive sync: enabled

Testing

VRRTest is a simple testing tool which should work for FreeSync and G-Sync. Install vrrtest-git^AUR or, manually install love package, clone repository, then run

$ love /path/to/cloned/repository

With VRR off, if the application's FPS is less than the monitor's native refresh rate then the bars will stutter a lot since frames are being skipped. With VRR active, the bars will always move smoothly across the screen since the screen's refresh rate will match the application's refresh rate. Even with VRR functional you may experience tearing in which case you can also enable the TearFree option for AMDGPU; with both enabled there should be neither stuttering nor tearing (what is the nvidia equivalent?).

If you are using a Nvidia GPU, you can test Gsync compatibility with gl-gsync-demo^AUR. This program will allow you to test VRR and Vsync so you can observe resulting effects. See project's Readme for more information.

According to this page: "gl-gsync-demo is made with G-SYNC but that does not matter, it will test AMD adaptive sync just fine". However, it may still not work as expected for FreeSync testing.

Change VRR Range of a FreeSync Monitor

Freesync monitors usually have a limited range for VRR that are much lower than their max refresh rate. It should be possible to overclock the monitor to change the Freesync range.

Warning: Overclocking your monitor may cause it to run hot and possibly cause harm. Proceed at your own risk.

Editing the EDID File

External Display Identification Data (EDID) stores driver information about your monitor. By default, this file is sent by your monitor and read on connect. You will need to extract this file using something like read-edid or nvidia-settings.

You can edit this file with wxedid^AUR

This article or section needs expansion.

Reason: This section needs verification from users with a freesync monitor please consider contributing. (Discuss in Talk:Variable refresh rate)

You may follow one of the guides of people changing the freesync range on Windows: [3][4]

Process of overclocking on Linux (works only on NVidia GPUs): [5]

Make a Xorg .conf file for your monitor and add a path to the custom EDID file you have edited. See xrandr to find find out the other information about your monitor.

/etc/X11/xorg.conf.d/10-monitor.conf

Section "Screen"
    Identifier "Screen0"
    Device "nvidia" # e.g. Radeon, nvidia
    Monitor "DP1"
    Option “CustomEDID” “MONITOR:/home/USER/Desktop/modified-edid.bin”
EndSection

Note: Edit “MONITOR” in the file to be the correct display ID. You can get the display ID with the xrandr -–query command.

Tips and Tricks

Remove applications from Blacklist

Mesa has a list of blacklisted applications to avoid unexpected behavior, you can edit this blacklist here:

/usr/share/drirc.d/00-mesa-defaults.conf

Limitations

Wayland is supported as of KDE 5.22 (any compatible GPU) and Sway (no Nvidia) [6] [7]. GNOME Wayland is not yet supported [8].
The monitor must be plugged in via DisplayPort. Some displays which implement (part of) the HDMI 2.1 specification also support VRR over HDMI. This is supported by the Nvidia driver and is supported by the AMD driver (pre HDMI 2.1) in Kernel 5.13 and later [9].
If you want to use Gsync and possibly Freesync on X11, only the Gsync/Freesync monitor must be connected.
- On X11, multiple monitors in a single X display will break Gsync/Freesync, however, this problem does not exist on Wayland.
- If on X11, if you want to use multiple monitors and still use Gsync/Freesync, you can create a new X display which only covers the Gsync/Freesync monitor and run games there.
Compositors will most likely need to be disabled before the OpenGl/Vulkan program is started (disabling compositors is not relevant or necessary on Wayland [10]).
On X11, Mesa blacklists many applications including video players.
Although tearing is much less noticeable at higher refresh rates, FreeSync monitors often have a limited range for their VRR of 90Hz, which can be much lower than their max refresh rate. See Change VRR Range of a FreeSync Monitor.