AMD officially only supports its latest FSR4 upscaling technology on the latest Radeon RX 9000 series GPUs, and this limitation is mostly down to the hardware requirements, which the predecessors lack. While the chipmaker did consider making it backwards-compatible for RX 7000 series GPUs, we still haven’t seen the effort bearing fruit yet – so a modder decided to step in and see what they can do.
FSR4 On 7900 XTX?
Reddit user Virtual-Cobbler-9930 posted their findings on this modding attempt, which is done on a Linux system with a specific Mesa driver that contains the necessary components to emulate FP8 matrix calculations required for FSR4 to work (while Optiscaler is used for the DLL injection). The RDNA 3 architecture that lies within the RX 7900 XTX does have AI accelerators of its own, but it’s designed for FP16 calculations – thus, emulation was required to perform the modification, and that comes with a sizeable trade-off in performance.
Still, that does translate to a better image quality in the three games tested, which includes Cyberpunk 2077, Oblivion Remastered, and Marvel Rivals. In the case of Cyberpunk though, converting from FSR 3 to FSR 4 incurs a 34% loss in framerates, though the user noted that this is still a number higher than native quality. The other two games saw roughly 30% losses on average, with the latter in particular dropping below 60 FPS, which is not ideal for a fast-paced competitive game.
Another limitation is the settings that can be used to gain framerates. The user conducted the comparisons under Quality preset, and noted that performance gains can be “almost nullified at lower resolutions like 1080p,” as RDNA3’s hardware simply couldn’t perform upscaling calculations any faster. This could reasonably explain why AMD limits FSR4’s availability to its newest cards only, at least for the time being.
Pokdepinion: Now the limitation makes a lot more sense.
