ComputerBase tests leaked FSR 4 INT8 version: works on RDNA 2 & 3, image quality falls short of FP8 but it is still better than FSR 3.1

ComputerBase conducted a deeper analysis of the leaked FSR 4 INT8 version, also known as the unofficial build for pre-RDNA 4 architectures. A quick recap: AMD accidentally released the full source code for its FSR 4 technology. This was unintentional , as AMD no longer plans to distribute full source code. However, the release included AI model weights which, on their own, were of little use to gamers. Modders later compiled complete DLL files that acted as drop-in replacements and worked as expected with games supporting previous versions of AMD’s upscaling technology.

The INT8 version is considered unofficially compatible with RDNA 2 and RDNA 3, as these architectures lack hardware acceleration for FP8 (Floating Point 8-bit), the format used by Radeon RX 9000 series cards. As a result, both versions differ in performance and image quality. While most reports focused on frame rate impact, ComputerBase also examined image quality in detail.

FSR 4 INT8 vs FP8: Image quality

ComputerBase found that the leaked INT8 (Integer 8-bit) version delivers a slightly less stable image than the official FP8 build for RDNA 4. Differences depend on the game and scene but are consistent enough to notice during motion. Fine details like fences, roofs, and vegetation tend to flicker more on RDNA 2 and RDNA 3. In motion, characters such as Aloy in Horizon Forbidden West show more artifacts, and foliage appears less stable.

ComputerBase has conducted these analyses on several games, and the conclusion is clear: FSR 4 on RDNA 4 is visually inconsistent with the leaked FSR 4 on RDNA 3 and RDNA 2. The former has the edge, which is clearly noticeable in some games, but hardly noticeable in others. The good news, however, is that “FSR 4 Light” consistently looks significantly better than FSR 3.1—even if that’s no mean feat. But for visual reasons, it’s still worth using, despite lagging behind FP8.

— ComputerBase (translation)

Overall, FSR 4 INT8 retains many of the algorithm’s advantages but lacks the smoothness and precision of FP8 rendering on RDNA 4. The German media included two video comparisons, which can run side-by-side on their website .

FSR 4 INT8 vs FP8: Performance

Performance varies by architecture. On average, FSR 4 INT8 reduces frame rates by about 9–13% on RDNA 3 (RX 7800 XT) and RDNA 2 (RX 6800 XT) , while the official FP8 version on RDNA 4 (RX 9060 XT) shows only a 3–5%. The RX 9060 XT remains the most efficient, sometimes even outperforming FSR 3.1 by up to 17%.

Source: ComputerBase

FSR 4’s cost grows with lower resolutions and aggressive modes like Performance. In some titles, RDNA 2 cards outperform RDNA 3, for example, Cronos, while others, such as God of War Ragnarok, favor RDNA 3. The pattern is clear: RDNA 4 handles FSR 4 efficiently, RDNA 3 delivers moderate performance loss, and RDNA 2 runs near its limits but remains viable for testing.

We asked AMD, but there was no response

We reached out to AMD to ask whether FSR 4 would be officially supported on older GPUs, or if the upcoming FSR Redstone will expand compatibility. Available information suggests that Redstone may support more than just RDNA 4 GPUs , possibly explaining AMD’s decision not to release FSR 4 for earlier architectures. Redstone is expected within the next three months, but AMD has not responded to our inquiry after nearly a month.

Source: ComputerBase