I am trying to install a new graphics card on my system and the screen comes up flashing, with the screen split in the middle.
The left edge of the screen meets the right edge of the screen in the middle.
i have the same graphics card, amd-radeon 6670 manufactured by msi and amd a6 apu.
After installing 12.04 (amd64) I had to boot in recovery mode.
First choose Networking option to establish connection and remount hard drive in r/w.
Ctrl-D back to menu and choose the root console option.
While possibly extraneous I update my
Proprietary Catalyst driver worked pretty well, search for fglrx wiki and follow the distribution specific install guide.