Hi All,

I need some help understanding FSR and how to use it.

Until recently, my only piece of gaming hardware was the Steam Deck. On this, the native (OS level) FSR easy to understand: drop the in-game resolution to something less than the display’s native 1280×800 and enable FSR, which then upscales the image. This makes sense to me.

Recently, I got myself a dedicated gaming PC as well (running 6700 XT). I’ve been playing around with the FSR option using Hellblade Senua’s Sacrifice as a benchmark, running DX11 mode and without ray tracing. I’m using a 1080p display.

From AMD’s control software, a ‘Radeon Super Resolution’ (RSR) mode can be enabled, which I understand is basically the same FSR as is running natively on the Steam Deck. It does nothing if the in-game resolution is the same as the display’s native resolution, but as soon as the in-game resolution is lowered, it applies spatial upscaling. So I drop my in-game resolution to 720p, enable RSR, and I can see the upscaling at work. This also makes sense.

Where I get confused is how in-game FSR fits into the picture. So Hellblade has native (in-game) FSR implemented. When running at 1080p resolution with no FSR and all settings maxed, I typically have close to 100% GPU utilization. Now, when I enable FSR in-game, still running at 1080p resolution, the GPU utilization drops to 75-80% with almost no visual impact (slight sharpening it seems, but wouldn’t notice without side-by-side screenshots). Framerates are of course more stable with the lower utilization.

So I don’t quite understand how this works. Does the game automatically render at a lower resolution (without having to adjust the in-game resolution) and upscales? Or why is it not necessary here to change the in-game resolution? Do all games implement native FSR in this manner?

Also, should the two be used mutually exclusively? I tried enabling both (so enabling SRS in AMD’s control software, dropping in-game resolution to 720p, and enabling in-game FSR). It worked, but certainly looked strange; not sure how to explain, almost like this watery effect. I’m assuming in this instance upscaling was applied twice?

Anyway, some insight would be much appreciated!

  • ET3DBEnglish
    1·
    1 year ago

    First of all, it’s worth noting that FSR has several versions, namely 1,2 and 3. FSR 1 (what the Steam Deck, RSR and Hellblade offer) simply upscales. FSR 2 gets motion data, and extrapolates from multiple frames, so has significantly higher quality. FSR 3 adds frame interpolation.

    When it comes to game vs. drivers when using FSR 1, then main difference is that the game will render the UI natively over an upscaled image, while the drivers will upscale the entire frame including UI. Therefore the UI in the game implementation will look better.

    So it’s better to enable FSR in the game rather than the driver, and fall back to the driver only if the game doesn’t implement FSR. Most games implement FSR 2, which is significantly better than what the driver can do, but even with FSR 1, the UI difference will make the game implementation preferable.