A Boon for Linux Gaming! CachyOS Proton Gets a Major Update: Simpler FSR4 Enablement via OptiScaler for AMD GPUs
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A Boon for Linux Gaming! CachyOS Proton Gets a Major Update: Simpler FSR4 Enablement via OptiScaler for AMD GPUs
CachyOS has released a new build of Proton-CachyOS 11, version 11.0-20260601, built on top of Proton Experimental 11.0-20260529. The update meaningfully simplifies the process of enabling FSR4 through OptiScaler and ships a handful of additional quality-of-life improvements for Linux gamers.
Automatic DLSS DLL Download for FSR4 via OptiScaler
The headline change targets users who want to test FSR4 upscaling through OptiScaler. Previously, enabling this required manually sourcing DLSS DLL files. In this release, CachyOS has updated the PROTON_USE_OPTISCALER environment variable so that it also downloads DLSS DLL files by default. This exposes DLSS inputs to FSR4 and simplifies setup for games that rely on DLSS path redirection for upscaling — no more manual file hunting.
New PROTON_OPTISCALER_CONFIG Variable
A new companion environment variable, PROTON_OPTISCALER_CONFIG, has been added. It allows users to write configuration options directly into OptiScaler.ini without opening the file manually. The format is a semicolon-separated string of {section}.{option}={value} pairs — for example:
PROTON_OPTISCALER_CONFIG="Upscalers.Dx11Upscaler=fsr31;Upscalers.Dx12Upscaler=dlss"
To guard against errors, only options that already exist in OptiScaler.ini can be modified. Changes persist until OptiScaler is upgraded, downgraded, or the variable is applied again.
PROTON_OPTISCALER_CONFIG will strip all comments from the INI file. Back up your OptiScaler.ini before applying this variable if you want to keep those annotations.
What Else Is New
Game-Specific Fixes
This release also bundles targeted fixes for several titles:
- Mega Man Legacy Collection 2 — video playback fix
- The Legend of Heroes: Trails in the Sky FC — video color inversion fix
- Unravel and Unravel Two — crash fixes
About CachyOS and Proton-CachyOS
CachyOS is a high-performance Linux distribution based on Arch Linux, tuned for speed and low latency. Its custom Proton fork, Proton-CachyOS, layers additional patches and experimental features on top of Valve’s upstream Proton — and notably uses native, optimized libraries from the CachyOS distribution itself rather than the isolated Steam Linux Runtime environment. This design philosophy aims to reduce stuttering and improve game stability, making it a popular choice among Linux gamers who want to push performance further.
Users can find detailed documentation on all supported environment variables and configuration options on the CachyOS Wiki.
