AMD FSR 4 Activates on Radeon RX 6800 XT “RDNA 2” Graphics Card: 10-20% Performance Impact with Enhanced Image Quality

Recent reports indicate that AMD’s FidelityFX Super Resolution (FSR) 4 has been successfully activated on the Radeon RX 6800 XT, a graphics card utilizing the older RDNA 2 architecture.

FSR 4 Activation on RDNA 2 GPUs: Enhanced Image Quality Observed

Following the leak of AMD’s FSR 4 source code, users have begun to unlock this cutting-edge technology on various GPUs, including AMD’s own Radeon RX 7000 series and NVIDIA’s RTX 30 series, which are not officially supported. The leaked files were modified to implement the INT8 version of FSR 4, allowing its operation on non-RX 9000 (RDNA 4) GPUs; this is possible due to widespread support for these instructions across many architectures.

Notably, enthusiasts have managed to enable FSR 4 on older models, such as the Radeon RX 6800 XT. A member of the Chiphell Forums has reported success with the game Stellar Blade, which supports FSR 3. By utilizing OptiScaler—a custom modded DLL—the user activated FSR 4.0.2 in the game environment.

AMD FSR 4 Enabled On Radeon RX 6800 XT GPU Performance Comparison — Image Source: Chiphell Forums

While the introduction of FSR 4 resulted in noticeably enhanced visual fidelity compared to FSR 3, it did come with a performance trade-off. In Quality mode using FSR 3, the game achieved over 110 FPS. However, when switching to FSR 4 in Quality Mode, the frame rate decreased to approximately 100-107 FPS. Users reported a performance drop of 10-20%, which, although significant, still allows for viable gameplay at over 100 FPS. This suggests that enabling FSR 4 could be worthwhile for those seeking improved upscaling quality despite the reduced frame rates.

Older GPUs experience a more pronounced performance decline with FSR 4 compared to FSR 3, primarily due to the lack of official support and requisite hardware features. For instance, Radeon RX 9000 GPUs encounter only a minimal performance loss of 2-4% when employing FSR 4, and RDNA 3 GPUs see about a 7%-10% drop. By contrast, RDNA 2 GPUs such as the RX 6800 XT can suffer performance reductions as steep as 10-20%.

The substantial performance impact on RDNA 2 GPUs can be attributed to several factors, notably the absence of WMMA (Wavefront Matrix Multiply Accumulation) instructions. Consequently, RDNA 2 models must rely on alternative hardware functions like DP4a or integer units to carry out matrix operations.

In light of the source code leak, many users speculate that AMD may be planning to officially support FSR 4 for older GPU models in the future. Should this include RDNA 2 architecture, it could lead to much-improved support based on the current improvised custom modded DLLs available to the public.

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