Are you sure that you bought a modern system? ATI hasn't existed since 2006 and I believe AMD stopped using the brand name almost a decade ago; it's all AMD now. Also AMD GPUs have had really good FOSS support in the mainline kernel since the late 00's. Unless you were trying to get fglrx to work, in which case that was a huge mistake.
Thanks, sorry I meant AMD of course, Radeon RX 590 to be precise. Yes there was a driver available on AMD's site but I couldn't get it to work. Certainly my fault somehow, but at the end of the day it was much easier to just install Windows 10.
What that practically means is that any linux distro with a kernel at least that new should support your card without needing to download anything from AMD's website. (Generally speaking, downloading drivers from the manufacturer's website is a windows-ism. There are some exceptions, like Nvidia, but a machine well configured for linux use should aim to use hardware supported by FOSS drivers (such as your AMD card.))
