The standings don't change much with our 4K ultra test results, though AMD does close the gap with the RTX 4070 Ti just a touch. Overall, Sapphire ends up 3.4% slower than the RTX 4070 Ti, with a slightly larger lead in rasterization performance and a slightly worse loss in DXR performance. Specifically, it's 10.6% faster in our rasterization suite, and 21.2% slower in the DXR suite.
If you ever want a good reason for upscaling algorithms, 4K gaming will suffice. Not only can you get quite good results when doing a modest 2x upscaling (e.g. going from 2715x1527 to 3840x2160). That's because the more data you have, the 'easier' it is for AI and conventional algorithms to fill in the gaps.
Put another way, let's look at the extreme. Imagine a 2x upscale from 5x5 pixels to 7x7 pixels. The algorithm would need to interpolate from 25 total pixels to 49 total pixels, but there's simply not as much detail to start with. Conversely, when the target ends up being 8.3 million pixels interpolated from 4.1 pixels, there's a wealth of information available.
From a performance perspective, upscaling to hit 4K also has some great benefits. We explained why 4K requires so much more VRAM than 1440p or 1080p, and while games can do things in various ways, the end result is that rendering at 2K and then upscaling to 4K can result in some excellent performance gains with a relatively minimal loss in image fidelity. You're also not likely to be CPU limited when targeting 4K, which isn't always the case with upscaling to 1080p.
Native 4K performance in our rasterization suite ranges from 48.9 fps in A Plague Tale: Requiem to 107.1 fps in Far Cry 6. Only two of the games failed to average 60 fps or more (though Flight Simulator barely got there). But with the Sapphire RX 7900 XT, or the RTX 4070 Ti, every rasterization game is very much playable, particularly if you drop from ultra to high settings.
For our DXR suite, things aren't quite so nice. Only Spider-Man: Miles Morales and Metro Exodus Enhanced can even break 30 fps at native 4K, and Control nearly gets there with 29.5 fps. But the other three games are in the high teens or low 20s. Even with FSR2 upscaling, which only three of the six games support, getting to 60 fps might be a stretch.
You could of course use a different suite of games for testing to make the results look better, or use lower settings (particularly in the DXR games) to close the gap between AMD and Nvidia GPUs. Or you could enable upscaling where supported, in which case DLSS remains more widely used than FSR2. But ultimately, the RX 7900 XT and RTX 4070 Ti do deliver relatively similar overall experiences, even though AMD's card has 20GB while Nvidia's GPU only has 12GB of VRAM.