AMD Accidentally Posts FSR 4 Source Code, Hints at Wider GPU Support

AMD’s latest FidelityFX SDK update quietly introduced FSR 4 upscaling alongside FSR 3.1.5 frame generation, but the release also came with an unexpected twist: the company briefly uploaded the entire FSR 4 source code to GitHub.

Although the repository was quickly taken down, screenshots captured by outlets like Videocardz reveal some interesting details about AMD’s plans.

Two Flavors of FSR 4

The files showed two distinct versions of FSR 4:

One designed for FP8 numerical format, optimized for AMD’s new RDNA 4 AI accelerators.
Another experimental version built around int8, a lower-precision format.

The int8 version suggests AMD has at least explored ways to make FSR 4 compatible with older RDNA 3 GPUs, which lack the FP8 accelerators found in RDNA 4. Whether this version is functional-or ever intended for public release-remains unknown.

AMD accidentally posted FSR4’s Source Code and then tried to delete it all LOL
The repohttps://t.co/FOpsWIn5sf
Commit historyhttps://t.co/nIMoDMt0LF
– CaptainMcShotgun (@CaptMcShotty) August 20, 2025

Why int8 Support Matters

FSR 4 is AMD’s first upscaler restricted to a specific GPU family, breaking from its previous GPU-agnostic approach. By default, it only runs on RDNA 4 hardware thanks to its reliance on FP8.

An int8 variant could extend FSR 4’s reach to more GPUs, but with trade-offs:

FP8 offers higher accuracy, leading to better image quality.
int8 is less precise, which could result in a visual downgrade-similar to how Intel’s XeSS DP4a fallback looks worse than the XMX-optimized version.

AMD hasn’t officially commented on the int8 build, and given the accidental nature of the leak, it’s unlikely to be production-ready. Still, the fact that it exists shows AMD is at least testing broader support.

Meanwhile, the new FidelityFX SDK 2.0 now acts as a foundation for AMD’s future neural rendering efforts, including the upcoming FSR Redstone feature set. The SDK equips developers with the necessary tools to integrate FSR 4 and future technologies directly into their games.

Bottom line: AMD’s slip-up confirms it has experimented with FSR 4 on non-RDNA 4 GPUs, but only the FP8-based version is official for now. Wider GPU compatibility may come later-though possibly with compromises in image quality.