The last few releases of Ubuntu have given me a lot of trouble on a desktop with a pair of Radeon 7970 video cards. The Live CD would start up, but leave me with a blank black screen and a mouse cursor. Doing a console-only install worked fine, but as soon as I’d try to install an X server, the system would go back to showing nothing more than a black screen.

Various help forums discuss enabling the “nomodeset” option during installation (it seems lots of other folks have had problems getting Ubuntu to play nice with AMD/ATI video cards). By itself, that didn’t make any difference on my system, but the idea in this thread put me on the right track. Here are the steps I used to install Ubuntu 14.04 on a system with a pair of Radeon 7970 graphics cards:

1. When the Live DVD starts up, press the down arrow. A language selection screen should appear; use the arrow keys to select your language and press Return.
2. Press F6. A menu will appear with advanced installation options. Check the boxes for “nomodeset” and “free software only” (use the Return key to check them).
3. Press Escape to exit that menu and press Return to start the Live DVD.
4. After waiting a few minutes, my system still appeared hung on a blank screen. Press ctrl-alt-F1 to get to a console.
5. At the console, enter the command “sudo bash” to start a shell with administrative access.
6. Type “apt-get remove xserver-xorg-video-radeon” to remove the default Radeon driver.
7. Type “service lightdm restart” to restart the display manager. On my system, this took me to a regular desktop running from the Live DVD. From there I could install Ubuntu normally.
8. Once the install finished and the system restarted, I went into Settings → Software & Updates and checked the box to allow “Proprietary drivers for devices”. Close that dialog to apply the new setting, then open it up again. Select the “Additional Drivers” tab and change from the open-source driver to AMD’s fglrx-updates driver. Reboot and enjoy your new Ubuntu desktop.