I've recently acquired a used Sapphire HD 7850 and am using it on a system with dual boot set up between Win7 and Linux.
I had previously used Mint 17.2 (Cinnamon), but wasn't happy with general performance, which is why I have switched to the newer Kubuntu 15.04 for the purpose of testing.
I can use the fglrx from the repos (labeled 15.20.1013 by the CCC), but would like to check out the newest drivers.
Unfortunately I can't manage to install the newest fglrx (15.7) from the AMD site without the system booting to a completely unresponsive a black screen.
The installation itself did not give any error messages and I did follow the instructions provided by the installation guide from AMD.
Once I reboot however, I see the Kubuntu logo for a few seconds and then get the black screen.
It's not even possible to switch to a text console - I had to remove the manually installed driver through recovery mode and a root shell.
Is there any previous experience with this issue?