FSR 4 running on a Radeon RX 7900 XTX is possible, but performance takes a big hit

AMD's new AI-powered FSR 4 update dramatically improves the upscaler's image quality, with results that are finally on par with or in the same league as NVIDIA DLSS. The new FSR 4 technology is exclusive to AMD's new RDNA 4-powered Radeon RX 9000 Series, as the AI model requires more powerful hardware that supports FP8 (8-bit floating point) technology.

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This means that older Radeon GPUs, like the previous-gen flagship, the Radeon RX 7900 XTX, are not supported by the current version of FSR 4, with those GPUs limited to the inferior FSR 3.1. Well, officially, as Reddit user Virtual-Cobbler-9930 has managed to get FSR 4 running on the Radeon RX 7900 XTX in several games.

The method they used included a combination of FP16 emulation, a Linux operating system, and a Proton layer with an FSR 4 patch to run Windows apps and games. The result? FSR 4's impressive image quality is present on a Radeon RX 7900 XTX, but games run significantly slower compared to running the game with FSR 3.

In Cyberpunk 2077 at 4K without ray-tracing using the FSR 4 'Quality' preset, the game runs at 56 FPS, while it runs 51% faster with FSR 3 with a frame-rate of 85 FPS. Yes, this is a huge difference, which comes down to RDNA 3 AI hardware not being at the level of RDNA 4, alongside running several emulation layers to get FSR 4 working. The good news is that FSR 4 on the Radeon RX 7900 XTX does offer a performance boost compared to running the game natively in 4K, which sees 39 FPS become 54 FPS.

Here's a breakdown of the games tested in 4K on the Radeon RX 7900 XTX with FSR 4, FSR 3/3.1 performance. Virtual-Cobbler-9930 notes that as the performance gains with RDNA 3 are minimal due to the architecture, using FSR 4 at lower resolutions like 1080p won't offer any additional performance.