Valve Leaks AMD FSR 4.1 Support in Proton

Valve's Proton Experimental build leaked AMD's FSR 4.1 upscaler, revealing a specialized INT8 model designed for RDNA 3 hardware.

Valve has started integrating AMD's FSR 4.1 upscaler into its Proton compatibility layer to support the Linux-based SteamOS. While RDNA 4 GPUs utilize FP8 data types, RDNA 3 hardware lacks 8-bit floating point support and relies on INT8 data types. To bridge this gap, AMD converts the FSR 4.1 model to 8-bit integer data for RDNA 3 compatibility. Preliminary support appeared in a Proton Experimental build, where Valve accidentally leaked an officially signed FSR 4.1 INT8 model. A Redditor captured the file before its removal and used OptiScaler to force the DLL in games. The leaked model was observed running on the RDNA 3.5-based Radeon 890M GPU, confirming AMD's development of separate models to ensure the new upscaler functions across different hardware architectures.