Make games look loads better on your old AMD Radeon GPU with this new FSR 4 mod

Weeks after AMD FSR 4 source code was accidentally leaked online, gamers have been putting it to the test on older RDNA 2 and 3 cards, with some surprising results. According to the tests, running the upscaling tech on older AMD cards like the AMD Radeon RX 6800 XT results in far better image quality for the most part, with only a small drop in performance.

So far, AMD hasn't officially enabled FSR 4 on older graphics cards, limiting its accessibility to its brand-new RDNA 4 GPUs like the AMD Radeon RX 9070 XT, which we recommend in our best graphics card guide. These mods, however, prove that the new tech can work on older GPUs, even if it isn't the easiest process to enable.

This process was made possible by the FSR 4 source code leak a few weeks ago. Since then, modders have been trying to implement FSR 4 in games using older cards. Several posts have since popped up on Reddit showcasing the results, including this post where user nuubcake11 showcased FSR 4 working in Cyberpunk 2077 on an AMD Radeon RX 7900 XTX graphics card.

To get it working, nuubcake11 used a custom FSR 4 DDL file, which replaces FP8 with Int8. FP8 is an 8-bit floating-point number format designed for fast math in AI workloads, but these operations are only supported on the newer AI cores in RDNA 4 GPUs. Int8, by contrast, is a lower-precision 8-bit integer format that's more widely supported on older hardware like RDNA 3. By swapping FP8 instructions for Int8, and patching the result into the game using the open-source OptiScaler tool, they were able to make FSR 4 run on these older AMD GPUs that otherwise wouldn't support it.

The end result is much improved image quality, with only a small drop in frame rates. For example, nuubcake11 saw a frame rate drop from 84fps at 1440p, with maxed out graphics settings and ray tracing enabled, to 79fps after switching from FSR 3.1.5 to FSR 4. This small performance drop is offset by the improved graphics, which, given that FSR 3 looks horrible, may well be a worthwhile trade-off.

The process isn't perfect, however. Some users in this Reddit post, where user bukankema was able to run FSR 4 in Cyberpunk 2077 on an even older RDNA 2-era RX 6800 XT, using the GPU's shader cores to process the instructions, as these older AMD GPUs have no dedicated AI cores.

This user reports some unusual issues on Windows, including some ghosting. That appears to be limited to RDNA 2 GPUs, however, indicating that there are still some limitations if you enable FSR 4 in this way.

While AMD hasn't officially announced incoming FSR 4 support for these older GPUs, its upcoming FSR Redstone tech looks set to bypass AI cores completely, meaning you may be able to run AMD's next-gen FSR upscaling and frame gen tech on any GPU, including Nvidia ones.

Given FSR 4 a try on your own older AMD graphics card? Let us know about your experience, good or bad, by starting a conversation in our community Discord server with readers and staff alike.