I've attached the manuals for the two displays. The relevant pages seem to be:
Samsung Manual: p44 (labeled 42), discusses HDMI in CEA mode for 1080p Acer Manual: p12, standard timing table My best guess for what is happening is that Ubuntu's display output timing over HDMI is slightly out of sync with what the Acer monitor expects, and hence some kind of "re-sync" process is happening about once a second. Or the timing of the laptop's built-in display is slightly different than that of the external monitor, causing the noveau driver to freak out about once a second as it tries to reconcile this. In my Xorg log file, I see a lot of stuff like this: [ 1878.231] (II) intel(0): EDID vendor "LGD", prod id 489 [ 1878.231] (II) intel(0): Printing DDC gathered Modelines: [ 1878.231] (II) intel(0): Modeline "1920x1080"x0.0 138.50 1920 1968 2000 2080 1080 1083 1088 1111 -hsync -vsync (66.6 kHz eP) [ 1879.796] (II) intel(0): Allocated new frame buffer 3840x1080 stride 15360, tiled [ 2099.091] (II) intel(0): EDID vendor "LGD", prod id 489 [ 2099.091] (II) intel(0): Printing DDC gathered Modelines: [ 2099.091] (II) intel(0): Modeline "1920x1080"x0.0 138.50 1920 1968 2000 2080 1080 1083 1088 1111 -hsync -vsync (66.6 kHz eP) [ 2111.153] (II) intel(0): EDID vendor "LGD", prod id 489 [ 2111.153] (II) intel(0): Printing DDC gathered Modelines: [ 2111.154] (II) intel(0): Modeline "1920x1080"x0.0 138.50 1920 1968 2000 2080 1080 1083 1088 1111 -hsync -vsync (66.6 kHz eP) [ 2124.123] (II) intel(0): EDID vendor "LGD", prod id 489 [ 2124.123] (II) intel(0): Printing DDC gathered Modelines: But if I look at the monitor's own menu, I see that the reported refresh rates are H:68KHz, V:60Hz The differences here seem like a likely culprit to me. ** Attachment added: "display_manuals.zip" https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/964231/+attachment/3564050/+files/display_manuals.zip -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to xserver-xorg-video-intel in Ubuntu. https://bugs.launchpad.net/bugs/964231 Title: System Stutter When HDMI Monitor Is Connected Status in “xserver-xorg-video-intel” package in Ubuntu: Confirmed Bug description: With a fresh install of Ubuntu 11.10 x64, the system has many "microfreezes" when I connect an external monitor via HDMI. These last maybe 10ms and occur about once per second. As I move my cursor around the screen, it stops motion during these microfreezes, causing a very irritating stutter effect. This only happens when using HDMI- when connected via VGA to an external monitor, the system behaves smoothly as expected. I started a thread about this a long time ago, but I never did find an answer: http://ubuntuforums.org/showthread.php?t=1817910 ProblemType: Bug DistroRelease: Ubuntu 11.10 Package: xorg 1:7.6+7ubuntu7.1 Uname: Linux 3.3.0-030300rc7-generic x86_64 .tmp.unity.support.test.0: ApportVersion: 1.23-0ubuntu4 Architecture: amd64 CompizPlugins: [core,bailer,detection,composite,opengl,compiztoolbox,decor,grid,move,vpswitch,place,mousepoll,resize,wall,regex,session,snap,gnomecompat,imgpng,animation,expo,workarounds,unitymtgrabhandles,ezoom,fade,scale,unityshell] CompositorRunning: compiz Date: Sat Mar 24 18:30:09 2012 DistUpgraded: Fresh install DistroCodename: oneiric DistroVariant: ubuntu ExtraDebuggingInterest: Yes, if not too technical GraphicsCard: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0116] (rev 09) (prog-if 00 [VGA controller]) Subsystem: Device [1b0a:2080] InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012) MachineType: PEGATRON CORPORATION A15 ProcEnviron: PATH=(cususername, no user) LANG=en_US.UTF-8 SHELL=/bin/bash ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.3.0-030300rc7-generic root=UUID=a19e39dd-b510-4f9d-93f5-de6d40df10f1 ro quiet splash vt.handoff=7 SourcePackage: xorg Symptom: display Title: Xorg freeze UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 06/17/2011 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: 211 dmi.board.asset.tag: ATN12345678901234567 dmi.board.name: A15 dmi.board.vendor: PEGATRON CORPORATION dmi.board.version: 1.0 dmi.chassis.asset.tag: No Asset Tag dmi.chassis.type: 9 dmi.chassis.vendor: PEGATRON Computer Inc. dmi.chassis.version: 1.0 dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr211:bd06/17/2011:svnPEGATRONCORPORATION:pnA15:pvr1.0:rvnPEGATRONCORPORATION:rnA15:rvr1.0:cvnPEGATRONComputerInc.:ct9:cvr1.0: dmi.product.name: A15 dmi.product.version: 1.0 dmi.sys.vendor: PEGATRON CORPORATION version.compiz: compiz 1:0.9.6+bzr20110929-0ubuntu6.1 version.ia32-libs: ia32-libs N/A version.libdrm2: libdrm2 2.4.26-1ubuntu1 version.libgl1-mesa-dri: libgl1-mesa-dri 7.11-0ubuntu3 version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A version.libgl1-mesa-glx: libgl1-mesa-glx 7.11-0ubuntu3 version.xserver-xorg: xserver-xorg 1:7.6+7ubuntu7.1 version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.6.0-1ubuntu13 version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.99~git20110811.g93fc084-0ubuntu1 version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.15.901-1ubuntu2.1 version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20110411+8378443-1 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/964231/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp
