After AMD recently leaked its own FSR 4 libraries on its GPUOpen GitHub repo , replete with libraries that support older hardware, it was only a matter of time before enterprising modders started demonstrating how those libraries could be used to port FSR to older RDNA GPUs. An enterprising Reddit user and modder recently posted a how-to guide explaining how to get FSR 4 implemented in games on RDNA 2 GPUs, and the results reveal improved image quality at the cost of performance. There are other caveats, as well, like having to use a very outdated driver or dive deep into configuration files to rename DLL files to get the upscaler working.

According to both the results posted in the Reddit thread and testing done by Computerbase , FSR 4 seems to offer a balance between native image quality and FSR 3.1 performance on both RDNA 3 and RDNA 2 hardware. Computerbase tested Cyberpunk 2077 in 4K on the Ultra settings preset using the AMD Radeon RX 7900 XTX, and FSR 4 delivered 11% faster performance than native, but fell short of FSR 3.1 frame rates by 16%. The Reddit user who posted the how-to guide tested an AMD RX6950 XT across a range of FSR 4 quality presets, and found that even when set to "Quality," the RDNA 2 GPU gained around 10% performance compared to native rendering in The Last of Us Part 2 at 1440p. Both sources comment that the image quality is a noticeable improvement over FSR 3, and it was more stable than XeSS, which, to its credit, beat out FSR 4 on RDNA 2 in The Last of Us Part 2 by up to 10%, depending on the quality preset. Curiously, similar performance deltas were observed when comparing the unofficial INT8 FSR 4 libraries on RDNA 4 to the officially supported FP8 libraries, and the performance difference between FSR 3.1 and FSR 4 is almost identical, as well.