Just installed Ubuntu 20.04 as a dual boot with Windows 10. When I ran the installer from a USB drive, I got a black screen until I rebooted and chose the "safe graphics" (I think that's what it was called anyway) option. This gave me a low-res display that was fine to install.
Now that the install is complete, on booting I again get a black screen. I can get past this by adding the
nomodeset option. With this I get something on screen, but it's low resolution and quite terrible.
It seems that there is a driver problem with my AMD Radeon R9 380 card. The additional drivers tool doesn't offer me anything to install.
Details of my machine: