Key Takeaways
- FSR 4 is AMD’s strategic shift to ML-based upscaling, delivering a massive ‘night-and-day’ improvement in image quality and stability over FSR 3.1.
- The full FSR ‘Redstone’ suite (including ML Ray Regeneration and Radiance Caching) is officially exclusive to the RDNA 4 (RX 9000) series due to specialized FP8 hardware requirements.
- Community modders have compiled a leaked INT8 version of FSR 4, enabling users to force the superior upscaler onto older RDNA 3 (RX 7000) and NVIDIA RTX 30/40 GPUs via the OptiScaler tool.
I. The Redstone Revolution: What FSR 4 & Redstone Actually Are
FidelityFX Super Resolution 4 (FSR 4) marks a fundamental strategic pivot for AMD, moving from a spatial/temporal reconstruction approach to a cutting-edge Machine Learning (ML)-based upscaler. Developed using code derived from the ROCm project (AMD ML2CODE) and trained on high-quality game data via AMD Instinct accelerators, FSR 4 delivers substantial image quality improvements over FSR 3.1. The subsequent FSR ‘Redstone’ branding encompasses FSR 4’s ML upscaling and adds two critical, next-generation features—Neural Radiance Caching and ML-based Ray Regeneration—that directly challenge NVIDIA’s DLSS 4.
| Criteria | FSR 3.0 | FSR 4.0/Redstone |
|---|---|---|
| Upscaling Methodology | Temporal Reconstruction | ML-Accelerated Upscaling (FP8/INT8) |
| Frame Generation | Yes (Analytical) | Yes (ML-Based) |
| Ray Regeneration | No | Yes (ML-Based) |
| Neural Radiance Caching | No | Yes |
| Official Minimum Hardware | RX 590+ | RX 9000 Series (RDNA 4) |
II. The Hardware Divide: Why FSR 4 is Exclusive to RDNA 4
Historically, FSR was defined by its open-source, vendor-agnostic nature. FSR 4 and the full Redstone suite break this tradition. The official reason for the strict limitation to the RX 9000 series (RDNA 4) is the reliance on RDNA 4’s enhanced second-generation AI accelerators. These dedicated units are specifically designed to handle emerging data types like FP8 and structured sparsity, offering up to 8x INT8 throughput for sparse matrices. The new ML-based upscaling and Ray Regeneration require this dedicated matrix math ability, making RDNA 4 the first architecture truly optimized for the Redstone suite.
FSR 4/Redstone: The Strategic Trade-Off
The Pros (Advantages)
- Massive Image Quality (IQ) Leap: Eliminates ghosting, shimmering, and blur from FSR 3.1.
- Feature Parity with DLSS 4: Introduces ML Ray Regeneration and Radiance Caching.
- Developer Simplicity: Eliminates the need for complex Reactive and Transparency masks.
- Superior Performance Potential: Achieved a 236% frame rate increase in Spider-Man 2 (Performance Mode).
The Cons (Disadvantages)
- Strict RDNA 4 Exclusivity: Alienates current RDNA 3 (RX 7000) owners.
- Performance Cost: The ML algorithm is notably slower than FSR 3.1 on older hardware.
- Slower Adoption: Far fewer native titles support FSR 4 at launch compared to DLSS 4.
- Initial Debut: Ray Regeneration debuted in the critically panned Call of Duty: Black Ops 7.
III. The Community Bridge: Unlocking FSR 4 on Older GPUs via OptiScaler
Despite AMD’s official stance, the open nature of FSR’s development led to an inadvertent release of source code containing an INT8 version of the FSR 4 model. Since the INT8 format is more widely compatible than the RDNA 4-native FP8 format, community modders quickly compiled a functional DLL. This breakthrough allows users with older RDNA 3 (RX 7000) cards and even NVIDIA RTX 30/40 series GPUs to bypass the hardware lock and utilize the superior FSR 4 upscaler in games. This critical vendor-agnostic functionality is achieved through the popular third-party bridging tool, OptiScaler.
This process involves using third-party software (OptiScaler) and compiled, leaked code. While functional, it is not supported by AMD, may conflict with anti-cheat systems, and requires specific configuration (like forcing DX12 mode in many games) to avoid crashes or visual artifacts.
Step-by-Step: How to Force FSR 4.0.2 on Unsupported Hardware
- Ensure your game is running in DirectX 12 mode (DX11 inputs often cause shimmering or failure).
- Download the latest OptiScaler files from the official Github repository.
- Extract the files into the game’s executable directory and run the setup file (e.g., ‘setup-windows.bat’).
- Replace the existing OptiScaler upscaler DLL with the compiled FSR 4.0.2 INT8 DLL (often named ‘amd_fidelityfx_upscaler_dx12.dll’).
- Launch the game and press the ‘Insert’ key to open the OptiScaler menu.
- In the menu, select ‘FSR 3.X’ as the primary upscaler, then navigate to FFX Settings and specifically choose ‘FSR 4.0.2’ to activate the ML-based algorithm.
IV. Image Quality Analysis: FSR 4 vs. DLSS 4
The key measure of FSR 4’s success is its visual fidelity. Testing confirms FSR 4 is a game-changer for AMD, often matching the quality of NVIDIA’s older DLSS 3 CNN model and sometimes even surpassing it in specific scenarios like disocclusion and particle density. For example, FSR 4 shows fewer sizzling artifacts around characters and handles dense spore clouds and confetti with superior sharpness compared to DLSS 3. We have observed that AMD has gone from the worst to the best disoccluder at 1440p. However, the newest DLSS 4 Transformer model retains the overall fidelity crown, particularly excelling in preserving fine geometric details (like wires and lines) and maintaining edge stability in extreme motion.
FSR 4 and Redstone: Essential Questions Answered
Will FSR Redstone ever officially come to RDNA 3 (RX 7000) cards?
AMD SVP Jack Huynh has confirmed the technology is strictly limited to RDNA 4 (RX 9000) due to hardware requirements. Any use on older cards currently requires the community-developed OptiScaler mod.
How does FSR 4 compare to native rendering?
FSR 4’s Native AA mode (1.0x scale factor) delivers image quality superior to native rendering at a modest performance cost, while the Quality mode (1.5x scale factor) achieves equal or superior IQ with significant performance gain.
What is the official release date for the full FSR Redstone suite?
AMD has scheduled the official Redstone premiere event for December 10th, 2025, though the Ray Regeneration feature has already soft-launched in Call of Duty: Black Ops 7.
FSR 4 is the necessary technological leap AMD needed, finally making FSR a truly competitive upscaler that can go toe-to-toe with DLSS 3 and challenge DLSS 4. The image quality gains—especially the elimination of artifacts like ghosting and shimmering—are undeniable. However, by strictly limiting the technology to RDNA 4, AMD has created a massive strategic blunder that alienates its existing user base. The true narrative of FSR 4 is not AMD’s official launch, but the swift, vital community effort to unlock the technology for everyone via OptiScaler, maintaining the open-source spirit AMD itself chose to abandon.
