CachyOS gets with FSR4 enhancements, HDR detection
OptiScaler support gets easier to configure.
CachyOS has released a new Proton-CachyOS 11 build based on Proton Experimental 11.0-20260529. The update includes several Linux gaming changes, but the most interesting part is for users testing FSR4 through OptiScaler.
The project has changed “PROTON_USE_OPTISCALER” to also download DLSS DLL files by default. This is done to expose DLSS inputs for FSR4, which should make the setup easier in games where OptiScaler depends on DLSS paths to redirect upscaling.
This update follows earlier experimental OptiScaler support . At the time, the feature was controlled through “ PROTON_USE_OPTISCALER=1, ” while another variable allowed users to select the injected DLL name. This new release builds on that work by handling more of the required DLL setup automatically.
Source: Github
CachyOS has also added “ PROTON_OPTISCALER_CONFIG ,” a new environment variable that can write settings directly to “OptiScaler.ini”. There are some limits. CachyOS says only existing options in “OptiScaler.ini” can be modified, which should reduce configuration errors. The changes are also permanent until OptiScaler is upgraded, downgraded, manually edited, or changed again through the environment variable. The project warns that using this option will remove comments from the INI file, so users should keep a backup.
The same Proton-CachyOS release also adds automatic HDR detection, several Wayland fixes, and automatic DXVK-Sarek selection for GPUs without Vulkan 1.3 support. Game fixes include Mega Man Legacy Collection 2, The Legend of Heroes: Trails in the Sky FC, Unravel, and Unravel Two.
What’s CachyOS and Proton
CachyOS is a performance-focused Linux distribution based on Arch Linux. It also maintains Proton-CachyOS, a custom Proton build for Steam and umu-launcher. Proton itself is Valve’s compatibility layer that allows many Windows games to run on Linux through Wine, but Proton-CachyOS is not the same as Valve’s official Proton build . It is a community-maintained version with extra patches, experimental features, and additional tools such as OptiScaler, DXVK-Sarek, and other gaming-focused changes.
CachyOS Proton Version 11.0-20260601
- Wine Wayland improvements imported from Proton-EM
- Fixes for unmanaged windows and server-side decorations
- WOW64 regression fix for Wine Wayland
- Keyboard focus loss fix with keyboard hooks
- Window surface handling fixes
- Automatic HDR detection and enablement
- “DXVK_NO_HDR=1” option to disable HDR
- Note that GNOME does not yet expose HDR automatically
- Video playback fix for Mega Man Legacy Collection 2
- Upside-down video fix for The Legend of Heroes: Trails in the Sky FC
- Crash fixes for Unravel and Unravel Two
- Fixes for games crashing or failing to connect to servers
- Automatic DXVK-Sarek use when the primary GPU lacks Vulkan 1.3 support
- “PROTON_DXVK_SAREK=1” option to force-enable DXVK-Sarek
- “PROTON_DXVK_SAREK=0” option to disable DXVK-Sarek
- “PROTON_USE_OPTISCALER” now downloads DLSS DLLs by default
- DLSS inputs are enabled for FSR4 through OptiScaler
- New “PROTON_OPTISCALER_CONFIG” variable for OptiScaler.ini settings
- OptiScaler config changes are permanent until changed manually or by version update
- Using the config variable removes comments from OptiScaler.ini
Source: CachyOS Proton (Github)
