Valve Briefly Exposes FSR 4.1 INT8 Build Through Proton Experimental

Valve may be preparing FSR 4.1 support for Proton Experimental after an early build briefly appeared in a Steam depot.

According to a Radeon subreddit post, Valve reportedly pushed a Proton Experimental manifest containing an FSR 4.1.1 INT8 build before removing it shortly after. Some users claim they downloaded the manifest before it disappeared.

The leaked package reportedly includes amdxcffx64.dll, a file tied to AMD’s FSR upgrade path. The same post claims the DLL is signed, which could make it useful in games that check DLL signatures before loading upscaling files.

FSR 4.1 Leak Points to Early Proton Work

The timing is notable because AMD has already confirmed plans to bring FSR 4.1 to older Radeon hardware. Radeon RX 7000 series GPUs based on RDNA 3 are expected to receive support in July 2026, while RDNA 2 hardware, including Radeon RX 6000 series cards, is planned for early 2027.

That makes the Proton Experimental leak more interesting for Linux users. It suggests Valve may already be preparing Proton support ahead of AMD’s wider FSR 4.1 rollout.

The build was reportedly labeled “FSR 4.1.1 INT8.” This matters because RDNA 3 uses an INT8 path instead of the FP8 model associated with newer RDNA 4 hardware.

RDNA 3.5 Testing Raises New Questions

Community testing reportedly shows the leaked FSR 4.1 INT8 build working on RDNA 3.5 hardware, including the Radeon 890M iGPU. AMD has not officially confirmed FSR 4.1 support for RDNA 3.5.

AMD’s Frank Azor recently said no final decision had been made about excluding RDNA 3.5 from FSR 4.1 support, leaving the door open for future support.

For RDNA 3 users, the leak may simply offer an early look at AMD’s official July update. For RDNA 3.5 users, it is more interesting because it suggests the INT8 version can run on that architecture.

Most Users Should Wait for the Official Release

The leaked build will likely appeal most to Linux users, modders, and enthusiasts who already experiment with Proton, OptiScaler, and DLL replacement tools.

However, most Radeon users should wait for AMD’s official rollout and proper driver support. Leaked builds can behave unpredictably, and Valve removed the manifest shortly after it appeared.

Still, the brief appearance of FSR 4.1.1 INT8 in Proton Experimental suggests Valve and AMD may be moving closer to broader FSR 4.1 support on Linux.

Via VideoCardz