AMD Source Code Leak Enables FSR 4 On Radeon RX 7000 And GeForce RTX 30 GPUs

Yesterday on Reddit, intrepid user u/AthleteDependent926 posted a bombshell to the r/Radeon subreddit: AMD's FSR 4 source code leak in August contained all the files needed to run FSR 4 with older GPU hardware. Doing so requires the use of OptiScaler, which we previously covered allowing users to enable FSR 4 in games that only supported DLSS or XeSS. That was for GPUs that already had AMD FSR 4 support, though; now, the floodgates are open for any user with a graphics card supporting INT8 calculations, a category that includes both AMD's RDNA 2 and RDNA 3 GPUs, as well as Intel's Arc and NVIDIA's GeForce RTX GPUs.

While the source code that AMD accidentally released included an INT8 version of the FSR4 model—it normally uses the FP8 format that is only supported by RDNA 4—it was just source code, which means that it wasn't in a form that users could actually make use of. Redditor u/AthleteDependent926 took the time to compile the source to a functional .dll that users could actually swap in to enable FSR 4. Just one problem: the same DLL also supports FSR 3, so directly swapping it doesn't do anything. You need to use OptiScaler so that you can select FSR 4.0.2 in the "FSR 3.X" settings dialog, as seen below:


In subsequent testing performed by u/nuubcake in Cyberpunk 2077 @ 1440p, ray-traced maximum settings, FSR 4 continued to turn around impressive results. Running on a Radeon RX 7900 XTX, FSR 3.1.5 managed 84 FPS but still suffered some motion shimmering characteristic to older versions of FSR. FSR 4 looked much sharper and clearer in motion, but also cost about 6-7 FPS on average, resulting in an average 79 FPS. Now, these aren't exactly industry-grade benchmarks like we've done for the Radeon RX 7900 XTX, but since FSR is largely GPU-bound, these results do still bode well for users on older architectures.

If you'd like to try this out for yourself, the process isn't difficult, but is a bit complicated. You'll need to grab the latest version of OptiScaler from its Github page, extract those files into your game's executable directory, and then run the "setup-windows.bat" or "setup-linux.sh" as appropriate. From there, download the "amd_fidelityfx_upscaler_dx12.dll" from u/AthleteDependent926's Reddit post and replace the one from OptiScaler with that one. Finally, launch the game, and once you're in-game, press Insert to open the OptiScaler menu, then select "FSR 3.X" as your upscaler before finally picking "FSR 4.0.2" in the FFX Settings area.

Given that AMD FSR 4 apparently can be made to run on older GPU architectures, this may leave some users displeased with AMD. Why arbitrarily lock FSR 4 behind RDNA 4? We don't think this was necessarily an anti-consumer move. As the original leaker states, FSR 4 running on INT8 does indeed have wider compatibility, but the official FSR 4 running on FP8 calculations has less processing overhead on RDNA 4, and may also have improved visual results versus the older INT8 version from the source leak. That's a trade-off that many enthusiasts may be willing to make, though.