Can someone explain to me why the 4090 scales poorly at lower resolutions? Is it because of drivers that have significant overhead, as HardwareUnboxed suggests, or is it because it lacks a certain scheduler, if I understood correctly?
It's none of those reasons, the driver overhead limits your max fps but strictly speaking that doesn't deal with across resolutions scaling.
The reason it's scaling less at lower resolutions is because the easiest way (and universal across all games) to put all the shader cores to work is to simply increase the number of pixels that they have to work on. Thus a GPU with so many cores like a 4090, the only way you can get close to actually utilising all those (or near all) cores is to increase the resolution - otherwise the game has to individually have specific settings, or be coded in a way, that properly distributes work across all said cores. Due to how unique and different each game engine & even just how each game might use a particular engine are, that means you generally won't see a high utilisation of the card except by upping the resolution. Plus some (rendering) work (in games) has to be done in a certain order/at a certain time, so you'll never get that full parallelization that you might get in for ex. rendering a scene with blender, super-computer simulations with tailor-made software etc.
There's a lot more to it, but that's the gist. If you want some interesting reading you can look into the changes AMD did from GCN to RDNA wrt bundling work et al; Vega f.ex. was a monster on paper, with lots of cores, but had trouble putting them all to work, so in practice it ended up disappointing in games compared to on-paper specs. Actually utilising the hardware is no small task, and a lot of work has to go into how the hardware is designed as well as thinking about the software it's meant for and what the needs/can use. A lambo going off-road is not gonna be very speedy.
With the launch of the Big Navi graphics cards, AMD has finally returned to the high-end GPU space with a bang. While the RDNA 2 design is largely similar to RDNA 1 in terms of the compute and graphics pipelines, there are some changes that have allowed the inclusion of the Infinity Cache and the …
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