A Reddit user has shared on r/radeon how they were able to run FSR 4 on their Sapphire Radeon RX 7900 XTX, despite not being officially supported by AMD. Currently, FSR 4 only runs on AMD’s 9000-series GPUs because it requires architecture that isn’t readily available on older CPUs. However, Reddit user Virtual-Cobbler-9930 said that the latest Mesa update for Linux allows the older GPU to emulate FP8 precision via FP16, which FSR 4 uses for its machine learning-powered upscaling. This means that the 7900 XTX can run it even without the necessary hardware — albeit, at the cost of some performance.
Virtual-Cobbler-9930 used the OptiScaler DLL injection tool to force games to support FSR 4, which modders previously used to enable it manually in games that only supported DLSS 2 or XeSS. After that, you only need a couple of commands, and you’re golden. According to the user, a stable release of Mesa is expected to arrive by August, so these patches should be automated with the driver by then — that is, unless AMD asks them to remove the feature.
Aside from the RX 7900 XTX GPU, the user also had an AMD Ryzen 7 7700X CPU set to a 65-watt limit and 128 GB of DDR5 RAM, running the Arch Linux operating system. They then tested three games with FSR 4 — Cyberpunk 2077, The Elder Scrolls IV: Oblivion, and Marvel Rivals. In general, FSR 4 was able to achieve a slightly better quality than FSR 3.1 in all titles and also provided better fps numbers compared to running the games in native 4K resolution.
FSR4 on RDNA3 (7900xtx) tests from r/radeon
