Yeah, and Ubuntu has a TONNN of drivers preinstalled and ready to go, but it might be a recent driver change that could have done that. And yeah, on Windows, without my drivers installed, the best resolution I get is 480 lol! I did notice that when I switched as well, that the basic video drivers are much better; however, mine still needed to be updated in order to work perfectly also
I really hope that all solves your issue!!