Modders Halve FSR 4 Render Times on AMD BC-250 Mining APU

FSR 4 Performance Boost on BC-250

Modders have significantly optimized FSR 4 performance on AMD's BC-250 mining APU, cutting the processing time for 1440p upscaling from 11.51 ms to 5.92 ms. This improvement also extends to 4K, where times dropped from 25.72 ms to 12.08 ms, and 1080p, from 7.13 ms to 3.93 ms. The optimized implementation produces byte-identical images, indicating efficiency gains without quality loss.

Portable FidelityFX DLL Implementation

The latest optimizations for FSR 4 on the BC-250 have been integrated into a portable FidelityFX DLL. This change moves the improvements from a custom Mesa modification, making the optimized path easier to use with existing OptiScaler installations or games that support native FidelityFX. This development is part of an ongoing community effort to adapt the PlayStation 5-derived crypto-mining board for Linux gaming.

Addressing RDNA 2 Limitations

The BC-250 uses older RDNA 2 graphics hardware, which is less suited for FSR 4's machine-learning and low-precision integer operations compared to newer AMD architectures. The optimizations address this by using more efficient mathematical paths for INT8 dot-product operations, specifically employing signed 24-bit integer operations instead of more expensive fallback sequences. One shader saw its instruction count reduced from 64,269 to 37,613.

Context and Future Scope

Testing was conducted on Linux using standard Mesa and GE-Proton, with native Windows support, other GPUs, and frame generation not yet qualified. The BC-250's practical upper target for FSR 4 remains around 1440p, as 4K still consumes 12.08 ms even after optimization. This work continues the unusual story of the BC-250, a crypto-mining board based on PS5 hardware.