VSR uses something akin to a virtual monitor and then scales via that, earlier you could add a custom resolution via regedit and just adding to the DAL override reg key but that seems to have stopped working in one of the Adrenaline drivers for 18.x for whatever reason. Although I heard adding a custom resolution from within Catalyst Next works but I have not tested that myself yet. For VSR itself I merely toggle it on and then check that GPU scaling is off but it's possible newer GPU's will be able to scale properly even with this enabled instead of limiting to some arbitrary limit because it's one res instead of another. (Something with how they scale via the GPU hardware at least according to AMD, of course if you use a even older driver this somehow just works anyway for the GPU's that aren't support so the validity of that has been a bit doubted.) EDIT: There are caps though, GCN 1.2 such as Fury supports up to 3840x2160 but no higher, Polaris and Vega scales to 5120x2880 (or the 16:10 variants of these.) For earlier GCN GPU models (GEN, 1.x it varies what people call this.) the limit is somewhere around 2560x1800 but can be overriden to a bit higher but not much.