When I played Doom 3, it was on a Dell Dimension 3000, only graphics expansion was through regular PCI slot, best card available for that was the Geforce 5200. I overclocked the Geforce, helped a little. Anyway, for the most part it ran ok, though in very busy parts framerate got close to single digits. But you, I still had fun and loved it.
I like good graphics, but I find it sad that for some it is the most important thing, to the point it is all they can talk about; this is also why I haver always liked Nintendo, they often focus on stuff other than power. Heck, I remember for the NES they had the power mat, you would walk on it to move your character. That said, I do hope that eventually they have a more powerful Switch with the newer Geforce architecture, but well, I am glad they use Nvidia GPUs rather than AMD ones.