last week I upgraded my kubuntu installation to Kubuntu 14.04, using . As far as I can tell, the system runs just fine.
After a few minutes of idling, my monitor goes blank, despite I disabled the setting in kde's energy options. The PC itself is running (no S3, etc.), I can even login via ssh. But the monitor won't react to mouse movement or keyboard input. It just stays blank. Switching to TTY1-8 won't help either.
My lucky guess: My LG-Monitor isn't being recognized correctly. EDID-Output: http://paste.ubuntuusers.de/419217/ - the interesting thing: KDE things, I'm using a monitor made by Goldstar Company Ltd. Xorg does not: xorg.0.log-grep: http://paste.ubuntuusers.de/419222/
There are no Errors [(EE)] in that file. Also, switching to fglrx driver didn't help.
$ lspci -v | grep -iA1 vga
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Barts XT [Radeon HD 6870] (prog-if 00 [VGA controller])
Subsystem: XFX Pine Group Inc. Radeon HD 8670
Any help or guess is appreciated.