Designed to run on an RDNA 3 Radeon RX 7000 GPU, FSR 4 improved image quality but not performance.
The shader-based upscaler on AMD FSR 3 is replaced by a new AI ML-based one on FSR 4, which significantly enhances image quality across the board. However, only RDNA 4-powered GPUs from the Radeon RX 9000 series may use the new technology. The earlier Radeon RX 7000 series GPUs based on RDNA 3, including the top-tier RX 7900 XTX, are excluded from the AI ML model since it is made for the newer high-throughput data formats that the AI accelerators of RDNA 4 GPUs can accelerate. The good news is that attempts are being made by the modding community to make FSR 4 compatible with RDNA 3 GPUs. The bad news is that performance has decreased even though FSR 4 on RDNA 3 shows a considerable improvement in image quality.
A game modder named Virtual-Cobbler-9930 found a way to make FSR 4 function in games like “Cyberpunk 2077,” which didn’t even have an official FSR 3.1 implementation. Games are generally expected to support FSR 3.1 in order to support FSR 4 through patches. The FSR 3.1 requirement is no longer required because Virtual-Cobbler-9930 discovered a method to inject FSR using a program called OptiScaler. The command “WMMA_RDNA3_WORKAROUND,” which can be used to activate FSR 4, is available. But it’s important to keep in mind that an RDNA 3 GPU, which doesn’t handle many of the high-throughput data sets that RDNA 4 GPUs do, will start to suffer greatly from the ML-based upscaler of FSR 4. This was verified during the “Cyberpunk 2077” test run, where the in-game benchmark tool revealed a decline in performance from 85 frames per second to 56 frames per second, despite gains in graphic quality. How Virtual-Cobbler-9930 got FSR 4 to work on “Cyberpunk 2077” in detail is shown in the source link below.
