Gamer enables AMD FSR 4 on RDNA 3 graphics cards

RX 7900 XTX user enables AMD FSR 4 on their graphics card, boosting image quality

When AMD unveiled FSR 4, the company confirmed that it would only be available on RDNA 4 graphics cards. Simply put, the AI advancements that AMD has made with RDNA 4 are what make AMD’s FSR 4 AI upscaler performant. As such, FSR 4 is not usable on older AMD GPUs. Regardless, an AMD Radeon RX 7900 XTX user has managed to enable FSR 4 on their RDNA 3 graphics card, highlighting notable improvements in image quality.

A Reddit user called Virtual-Cobbler-9930 has tested FSR 4 on their RX 7900 XTX. Performance-wise, this results in large FPS drops when compared to AMD’s older FSR 3 non-AI upscaler. With FSR 3 in Quality mode, an average framerate of 85.06 was achieved in Cyberpunk 2077. However, with FSR 4, the framerate dropped to 56.28 FPS.

In The Elder Scrolls IV: Oblivion Remastered, moving from FSR 3 to FSR 4 dropped framerates from 46 FPS to 36 FPS. Image quality was notably improved, but its impact on performance makes FSR 4 a poor option for Radeon RX 7900 XTX users.

Why does FSR 4 perform poorly on RDNA 3 GPUs?

Simply put, AMD’s RDNA 4 graphics card features stronger AI hardware than AMD’s last-generation RDNA 3 GPUs. RDNA 4’s AI units feature FP8 support and support for sparse matrices. With RDNA 4, AMD can deliver 8x the INT8 throughput of RDNA 3 on a per Compute Unit basis. As such, AMD’s RDNA 4 GPUs can complete AMD’s FSR 4 calculations at a much faster rate. This reduces the performance overhead of FSR 4 on RDNA 4 hardware to reasonable levels.

There are rumours that AMD plans to implement a version of FSR 4 on RDNA 3 graphics cards. If this is the case, AMD will need to optimise its FSR 4 algorithm to run well on its less performant RDNA 3 AI hardware. If RDNA 3 GPUs receive FSR 4 support, it will likely support a lower-end version of FSR 4 that can run faster on RDNA 3 graphics cards.

By enabling FSR 4 on their RX 7900 XTX, Virtual-Cobbler-9930 has showcased why AMD’s AI upscaler is not available on its last-generation GPUs. While RDNA 3 features AI accelerators (RDNA 2 and older AMD GPUs don’t), these accelerators are not fast enough to run AMD’s current iteration of AMD’s AI upscaler.

You can join the discussion on gamers enabling FSR 4 support on AMD’s RX 7900 XTX graphics cards on the OC3D Forums.