This monitor was correctly detected and worked properly at maximum resolution for the last 2 years, but X no longer correctly identifies the monitor and now only proposes a maximum display resolution of 1368x768 since a recent update.
ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: xorg (not installed)
ProcVersionSignature: Ubuntu 4.15.0-29.31~16.04.1-generic 4.15.18
Uname: Linux 4.15.0-29-generic x86_64
.tmp.unity_support_test.0:
ApportVersion: 2.20.1-0ubuntu2.18
Architecture: amd64
CompizPlugins: [core,composite,opengl,compiztoolbox,decor,vpswitch,snap,mousepoll,resize,place,move,wall,grid,regex,imgpng,session,gnomecompat,animation,fade,workarounds,scale,expo,ezoom]
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity
Date: Sun Jul 29 11:10:25 2018
DistUpgraded: Fresh install
DistroCodename: xenial
DistroVariant: ubuntu
EcryptfsInUse: Yes
ExtraDebuggingInterest: Yes, if not too technical
GraphicsCard:
Advanced Micro Devices, Inc. [AMD/ATI] Device [1002:67ef] (rev cf) (prog-if 00 [VGA controller])
Subsystem: XFX Pine Group Inc. Device [1682:9460]
InstallationDate: Installed on 2016-05-20 (800 days ago)
InstallationMedia: Ubuntu-Server 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.3)
MachineType: Gigabyte Technology Co., Ltd. GA-990FXA-UD3
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.15.0-29-generic root=/dev/mapper/Whiteygu-lvm--root ro
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 05/30/2012
dmi.bios.vendor: Award Software International, Inc.
dmi.bios.version: F8
dmi.board.name: GA-990FXA-UD3
dmi.board.vendor: Gigabyte Technology Co., Ltd.
dmi.board.version: x.x
dmi.chassis.type: 3
dmi.chassis.vendor: Gigabyte Technology Co., Ltd.
dmi.modalias: dmi:bvnAwardSoftwareInternational,Inc.:bvrF8:bd05/30/2012:svnGigabyteTechnologyCo.,Ltd.:pnGA-990FXA-UD3:pvr:rvnGigabyteTechnologyCo.,Ltd.:rnGA-990FXA-UD3:rvrx.x:cvnGigabyteTechnologyCo.,Ltd.:ct3:cvr:
dmi.product.name: GA-990FXA-UD3
dmi.sys.vendor: Gigabyte Technology Co., Ltd.
version.compiz: compiz 1:0.9.12.3+16.04.20180221-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.91-2~16.04.1
version.libgl1-mesa-dri: libgl1-mesa-dri 17.0.7-0ubuntu0.16.04.2
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 18.0.5-0ubuntu0~16.04.1
version.xserver-xorg-core: xserver-xorg-core N/A
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati N/A
version.xserver-xorg-video-intel: xserver-xorg-video-intel N/A
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau N/A
xserver.bootTime: Sun Jul 29 09:18:04 2018
xserver.configfile: default
xserver.errors: AMDGPU(0): Failed to open amdgpu hybrid version
xserver.logfile: /var/log/Xorg.0.log
xserver.version: 2:1.19.6-1ubuntu4~16.04.1
xserver.video_driver: amdgpu
This log shows that the probing detects the high resolution modes
[ 111.418] (II) AMDGPU(0): Printing probed modes for output DisplayPort-0
[ 111.418] (II) AMDGPU(0): Modeline "3840x2160"x60.0 533.25 3840 3888 3920 4000 2160 2163 2168 2222 +hsync -vsync (133.3 kHz eP)
[ 111.418] (II) AMDGPU(0): Modeline "3840x2160"x30.0 297.00 3840 4016 4104 4400 2160 2168 2178 2250 +hsync +vsync (67.5 kHz e)
but doesn't appear to determine anything via DDC on the displayport. Again this doesn't seem to have been an issue until the driver updates applied on the 23rd (dpkg.log in separate attachment),