Dual monitor works fine in Ubuntu 14.04 with additional drivers fglrx-updates. After activating skydome, I suppose, it worked like the following: It comes with two monitors up, after logging in, both monitors will go black until I plugged of the VGA Monitor and switching with Ctrl-Alt-F8 and Ctrl-Alt-F7. Then the first monitor HDMI comes back again. I cann finally replug the VGA Monitor and is detected well. The bug is similar to the unmaintained #1124328.
I have resetted graphics adapter and unity and compiz and xserver several many times. Behaviour is now stable.
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.tmp.unity.support.test.0:
ApportVersion: 2.14.1-0ubuntu3.4
Architecture: amd64
CompizPlugins: [core,composite,opengl,compiztoolbox,decor,resize,place,gnomecompat,mousepoll,regex,vpswitch,commands,animation,wobbly,imgpng,move,fade,session,workarounds,cube,showdesktop,scale,expo,rotate,ezoom,td,switcher,unityshell,unitymtgrabhandles,dbus]
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity
DistUpgraded: 2014-08-30 02:57:42,801 DEBUG enabling apt cron job
DistroCodename: trusty
DistroRelease: Ubuntu 14.04
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes, including running git bisection searches
GraphicsCard:
Advanced Micro Devices, Inc. [AMD/ATI] Broadway XT [Mobility Radeon HD 5870] [1002:68a0] (prog-if 00 [VGA controller])
Subsystem: ASUSTeK Computer Inc. Device [1043:1c02]
InstallationDate: Installed on 2013-10-20 (339 days ago)
InstallationMedia: Ubuntu-Server 12.04.1 LTS "Precise Pangolin" - Release amd64 (20120817.3)
MachineType: ASUSTeK Computer Inc. G73Jh
Package: xserver-xorg-video-ati 1:7.3.0-1ubuntu3.1
PackageArchitecture: amd64
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-36-generic root=UUID=40c86281-3fee-46aa-9513-7aa0779a2cab ro radeon.dpm=1
ProcVersionSignature: Ubuntu 3.13.0-36.63-generic 3.13.11.6
Tags: trusty ubuntu compiz-0.9
Uname: Linux 3.13.0-36-generic x86_64
UpgradeStatus: Upgraded to trusty on 2014-08-30 (25 days ago)
UserGroups: adm cdrom dip fuse lp lpadmin plugdev root sambashare sudo tomcat7
_MarkForUpload: True
dmi.bios.date: 01/27/2011
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: G73Jh.213
dmi.board.asset.tag: ATN12345678901234567
dmi.board.name: G73Jh
dmi.board.vendor: ASUSTeK Computer Inc.
dmi.board.version: 1.0
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: ASUSTeK Computer Inc.
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrG73Jh.213:bd01/27/2011:svnASUSTeKComputerInc.:pnG73Jh:pvr1.0:rvnASUSTeKComputerInc.:rnG73Jh:rvr1.0:cvnASUSTeKComputerInc.:ct10:cvr1.0:
dmi.product.name: G73Jh
dmi.product.version: 1.0
dmi.sys.vendor: ASUSTeK Computer Inc.
version.compiz: compiz 1:0.9.11.2+14.04.20140714-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.52-1
version.libgl1-mesa-dri: libgl1-mesa-dri 10.1.3-0ubuntu0.1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 10.1.3-0ubuntu0.1
version.xserver-xorg-core: xserver-xorg-core 2:1.15.1-0ubuntu2.1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.8.2-1ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.3.0-1ubuntu3.1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.910-0ubuntu1.1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.10-1ubuntu2
xserver.bootTime: Wed Sep 24 23:05:20 2014
xserver.configfile: default
xserver.logfile: /var/log/Xorg.0.log
xserver.version: 2:1.15.1-0ubuntu2.1
xserver.video_driver: radeon
apport information