How to Use FSR 4 on RDNA 2/3 Graphics Cards Following Recent Leak

In an interesting turn of events, the PC gaming community has managed to get AMD’s latest FSR 4 upscaling technology – which was only intended for the latest RX 9000 series – to run on older RDNA 2 and RDNA 3 graphics cards. This is after AMD accidentally leaked FSR 4’s source code on GitHub as part of their FidelitySDK, which sparked a predictable modding frenzy that has opened up the AI-powered upscaler to a much wider audience than AMD intended.

While the company quickly removed the source code, the “damage” was already done and users had downloaded the files, including crucial INT8 model libraries that would prove essential for running FSR 4 on older hardware.

AMD’s new RDNA 4 architecture (Radeon RX 9000 series) is still a better choice for FSR 4 because it requires FP8 (8-bit floating point) support for optimal performance. However, the greatly improved visuals with FSR 4 over FSR 3.1 may be worth incurring a performance hit.

Performance Impact by Architecture:

• RDNA 4 (RX 9000 series): 2-4% performance hit with official FP8 support
• RDNA 3 (RX 7000 series): 7-10% performance hit using INT8
• RDNA 2 (RX 6000 series): 10-20% performance hit using INT8

The performance penalty on older architectures stems from the lack of native hardware support. RDNA 2 GPUs must fall back on less efficient DP4a operations instead of the optimized WMMA (Wavefront Matrix Multiply Accumulation) instructions available on newer cards.

How to Enable FSR 4 on RDNA 2 Graphics Cards

Warning: This process involves using unofficial modifications and older drivers. Use at your own risk, and never attempt this with online games as it may trigger anti-cheat systems.

Prerequisites:

1. Older AMD Driver Required: For RDNA 2 cards, you must use AMD Radeon driver version 23.9.1. Newer drivers will cause compatibility issues. This means sacrificing two years of driver improvements and bug fixes.
2. OptiScaler Tool: This is the middleware that enables upscaler swapping in games.
3. Modified FSR 4 DLL: The INT8 compiled version that works with older hardware.

Installation Guide:

Step 1: Driver Preparation (RDNA 2 Only)

• Uninstall your current AMD drivers completely using DDU (Display Driver Uninstaller)

• Download and install AMD Radeon driver 23.9.1
• Do not update when prompted

Step 2: Download Required Files

1. Download the latest OptiScaler nightly build from the OptiScaler GitHub repository
2. Download the modified FSR 4 INT8 DLL file (amd_fidelityfx_upscaler_dx12.dll) from community sources

Step 3: Install OptiScaler

1. Extract all OptiScaler files into your game’s executable directory (where the .exe file is located)
2. Run the “OptiScaler Setup.bat” file (Windows) or “setup-linux.sh” (Linux)
3. This will automatically rename the necessary files for your specific game

Step 4: Replace the DLL

• Replace the OptiScaler’s default amd_fidelityfx_upscaler_dx12.dll with the INT8 version you downloaded

Step 5: Configure In-Game

1. Launch your game
2. Press Insert key on your keyboard to open the OptiScaler overlay (this can be changed in config)
3. Set the Input to whatever upscaler your game supports (DLSS, XeSS, or FSR 3)
4. Set the Output to “FSR 3.X”
5. In FFX Settings, select “FSR 4.0.2”
6. Choose your quality preset (Quality, Balanced, Performance, etc.)

Alternative Method: Manual DLL Replacement

For games that already support FSR 3.1 natively:

1. Navigate to the game’s installation folder
2. Locate the FSR DLL files
3. Back up the original files
4. Replace with the modded FSR 4 INT8 DLL
5. Rename files as necessary to match the original naming scheme

Known Working Games (via OptiScaler):

• Cyberpunk 2077
• Baldur’s Gate 3
• Dragon’s Dogma II
• Kingdom Come: Deliverance II
• Microsoft Flight Simulator 2024
• Red Dead Redemption 2
• Ratchet & Clank: Rift Apart
• Horizon Zero Dawn Remastered
• The Last of Us Part II
• Stellar Blade

A more comprehensive compatibility list is maintained on the OptiScaler GitHub wiki page.

Important Limitations:

1. No online gaming: Do not use with games featuring anti-cheat systems (EasyAntiCheat, BattlEye, etc.)
2. DirectX 11/12 only: Currently doesn’t work with Vulkan-based games
3. Driver restrictions: RDNA 2 users must stick with outdated drivers
4. Performance cost: Expect 10-20% lower performance compared to FSR 3.1 on RDNA 2
5. Experimental: This is unofficial and unsupported. Expect bugs and instability

Is It Worth It?

First of all, only do this if you enjoy tinkering and don’t mind troubleshooting. Whether it’s worth the trouble will depend on your specific situation. RDNA 3 GPUs are better than RDNA 2 thanks to minimal driver issues and a more reasonable performance hit. It also depends on whether you are already well above your desired FPS target, e.g. running at 100 FPS+.

If you have an RDNA 2 GPU and need the latest drivers for other games, however – or already struggle to maintain playable frame rates – then just skip this process. Also avoid if you play competitive online games.

And as always with unofficial modifications, proceed with caution.