“Substantially superior to FSR 3.1” — How modders forced FSR 4 upscaling onto unsupported AMD and NVIDIA cards

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When NVIDIA and AMD released their newest graphics cards, both companies included features that required the latest computer hardware to work.

For NVIDIA, the newest DLSS 4 technology had different features depending on the graphics card. The more advanced Multi Frame Generation was exclusive to the RTX 5000 series, while a slightly less powerful version, Enhanced Frame Generation, was available on the older RTX 4000 series cards.

AMD’s FidelityFX Super Resolution (FSR) 4.0 was limited to its newest RDNA 4 graphics cards, like the Radeon RX 9070 XT. Owners of older RDNA 3 or earlier GPUs couldn’t use the feature.

Things have just shifted thanks to dedicated Radeon users and leaked Int8 files related to FSR (as reported by Wccftech).

Last month, AMD mistakenly published the complete source code for FSR 4 on GitHub. While the error was quickly noticed and the code downloaded by some, the incident hadn’t received much attention until recently.

Recently, posts started appearing on the Radeon subreddit showing evidence that FSR 4 was working on graphics cards that weren’t officially supported.

I’ve been following this really cool thing that started on Reddit – a user named AthleteDependent926 shared something that’s gotten a ton of AMD Radeon GPU owners, including myself, experimenting and super excited. It’s been amazing to see what people are discovering!

How is AMD’s FSR 4 running on old GPUs that don’t technically support it?

AMD’s FidelityFX Super Resolution 4 (FSR 4) currently works officially only with their newest RDNA 4 graphics cards, because these cards support FP8 technology. Older RDNA 3 cards (and earlier models) don’t have FP8 support, which previously prevented them from using FSR 4. While Linux users could sometimes bypass this limitation, Windows users had no way to use the feature.

A recent leak on GitHub revealed files from AMD that let some users create their own version of a DLL for FSR 4.

Instead of using the FP8 format, a special version of FSR 4 was created using Int8 files. This makes it work with AMD’s RDNA 2 and 3 graphics cards, and even some older NVIDIA RTX 30-series cards. People using Windows have found they can successfully swap out FSR 3.1 for this FSR 4 version using a tool called OptiScaler, which easily replaces upscaling technologies in games.

I’ve been looking at what people are saying on Reddit, and the results with FSR 4 are actually pretty good. Though, it seems like getting it to run flawlessly on older graphics cards can be a bit tricky. One user, AthleteDependent926, explained it like this:

This Int8 version produces noticeably better image quality than FSR 3.1, and handles fine details like hair and objects far in the distance more effectively than XeSS (another Int8 model). However, it requires significantly more processing power – almost three times as much on RDNA 3 graphics cards (0.6ms compared to 1.9ms) and four times as much on an RTX 3060 Ti when compared to Transformer DLSS.

Reddit user nuubcake11 followed up the original post with some testing in Cyberpunk 2077.

The game functions with FSR 4 enabled when using an AMD Radeon RX 7900 XTX (from the RDNA 3 series) through OptiScaler.

I was really impressed – with AMD’s FSR 3.1.5 turned on, I was getting around 84 frames per second at 1440p, even with everything maxed out and ray tracing enabled. But when I switched over to a customized version of FSR 4, I saw a bit of a drop, down to about 79 FPS.

Many people notice a slight drop in frame rates, but they feel it’s worth it for the improved image quality. FidelityFX Super Resolution 4 significantly reduces distracting visual artifacts in fine details.

A gamer recently tested Cyberpunk 2077 using an RX 6800 XT graphics card, the CachyOS operating system, and AMD’s FSR 4 technology. They found that FSR 4 produced noticeably sharper visuals, though the performance wasn’t entirely consistent.

Some users are reporting ghosting problems with RDNA 2 graphics cards on Windows. If you don’t have a brand new RDNA 4 card, RDNA 3 still appears to be the better option.

What exactly is AMD’s FidelityFX Super Resolution?

AMD’s FidelityFX Super Resolution (FSR) is similar to NVIDIA’s Deep Learning Super Sampling (DLSS), as both technologies improve graphics by increasing resolution and creating extra frames for smoother performance.

Up to FSR 3, AMD used sophisticated algorithms to enhance image quality. With FSR 4, they moved to a more advanced approach using machine learning.

This update has significantly enhanced FSR’s capabilities, and FSR 4 is a substantial improvement over FSR 3. The video below clearly demonstrates the difference.

AMD hasn’t confirmed support for FSR 4 on older Radeon graphics cards, which is understandable given that early, unofficial versions haven’t been performing well for most people.

As a researcher, I’m currently watching to see if AMD will change its approach now that this unofficial workaround for FSR 4 is available. It’s a wait-and-see situation at this point.

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2025-09-16 17:41