Weeks after the inadvertent leak of AMD FSR 4 source code, the gaming community has eagerly embarked on a journey to test its capabilities on older RDNA 2 and 3 graphics cards, yielding some unexpected findings. Initial reports indicate that utilizing this upscaling technology on legacy AMD models, such as the AMD Radeon RX 6800 XT, enhances image quality significantly, with only a minor performance dip.
Modding the Future
Currently, AMD has not officially rolled out FSR 4 support for older graphics cards, confining its availability to the latest RDNA 4 GPUs, including the AMD Radeon RX 9070 XT, which features prominently in our recommended graphics card guide. Nevertheless, the recent modding efforts demonstrate that this innovative technology can indeed be harnessed on older GPUs, albeit through a somewhat intricate process.
The catalyst for this experimentation was the aforementioned source code leak, which has empowered modders to integrate FSR 4 into various games on older hardware. A notable example surfaced on Reddit, where user nuubcake11 showcased the successful implementation of FSR 4 in Cyberpunk 2077 using an AMD Radeon RX 7900 XTX graphics card.
To achieve this, nuubcake11 employed a custom FSR 4 DDL file that substitutes FP8 with Int8. While FP8 is an 8-bit floating-point number format optimized for rapid calculations in AI tasks—supported exclusively by the advanced AI cores in RDNA 4 GPUs—Int8 represents a more universally compatible 8-bit integer format, making it suitable for older architectures like RDNA 3. By replacing FP8 instructions with Int8 and utilizing the open-source OptiScaler tool to patch the game, they successfully enabled FSR 4 on GPUs that would otherwise lack support.
The results were promising, showcasing enhanced image quality with only a slight decrease in frame rates. For instance, nuubcake11 experienced a drop from 84fps at 1440p with maximum graphics settings and ray tracing enabled, down to 79fps after transitioning from FSR 3.1.5 to FSR 4. This minimal performance reduction is counterbalanced by the superior graphics quality, particularly given the subpar visuals associated with FSR 3.
However, the modding process is not without its challenges. In another Reddit discussion, user bukankema successfully ran FSR 4 in Cyberpunk 2077 on the even older RDNA 2 RX 6800 XT, utilizing the GPU’s shader cores for instruction processing, as these earlier models lack dedicated AI cores. This user reported some peculiar issues on Windows, including ghosting effects, although these appear to be specific to RDNA 2 GPUs, suggesting that limitations still exist when enabling FSR 4 through this method.
While AMD has yet to announce official support for FSR 4 on older GPUs, the forthcoming FSR Redstone technology is anticipated to circumvent the need for AI cores entirely. This development could potentially allow users to leverage AMD’s next-generation FSR upscaling and frame generation technology across a broader range of GPUs, including those from Nvidia.
If you have experimented with FSR 4 on your older AMD graphics card, we invite you to share your experiences—whether positive or negative—by engaging in a conversation on our community Discord server with fellow readers and staff.
