OP here. Sorry I went off radar for a while. I tried the 20131223 daily build of Ubuntu 14.04 Trusty Tahr Desktop AMD64, and it still had the problem when I booted the live CD. My up to date install of Ubuntu 13.10 (fresh install of that version) was also still having the same problem.
Seeing the Andrew had good luck updating his BIOS, I looked for updates for my own board. My BIOS version was "685 A105 x64", built around October of 2011. The EVGA website listed this BIOS as version A05. The website offered version R22, released 3-13-2013, for download. I installed that (had to do it from my Windows boot), and noted that my BIOS now says it's version "685 0.22 x64" and was built "03/01/2013 14:51:21". After this, both the daily build of Ubuntu and my up to date install of Ubuntu 13.10 both run fine without any acpi flag sent to the kernel. It looks like updating my BIOS solved the bug. Should this bug ticket's status be changed to "Fix Released", since a good BIOS has been released for this board? -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/973933 Title: Random Reboot if I Boot with ACPI On Status in “linux” package in Ubuntu: Expired Bug description: If I boot up Ubuntu 11.10 without sending the apci=off parameter to the kernel in GRUB, then after not too long (usually less then 10 minutes, always less than 20) my computer will randomly reboot. It's as if I forced the computer off by pressing the power button for a few seconds, then waited 2 seconds, then turned the computer back on. I have not noticed any trigger for the reboot; it seems completely random. I have tried these kernel parameters, but I have experienced the reboot on them all: acpi=ht pci=noacpi acpi=noirq pnpacpi=off noapic nolapic In troubleshooting before I figured out acpi=off worked, I tried swapping out lots of hardware. I narrowed it down to being either my motherboard or my CPU: Motherboard: EVGA Z68 SLI (model 130-SB-E685-KR) (Intel Z68 north bridge) CPU: Intel Core i7 2600 (Sandy Bridge) Attached are outputs of lspci -vvnn and dmidecode that I ran with ACPI on, before a random reboot stopped me. Also attached are outputs from uname -a, /proc/version_signature, and lsb_release -rd. /proc/acpi did not exist when I booted with ACPI. I have the linux-image-3.0.0-18-generic package, version 3.0.0-18.31, installed, but I have had this problem with the Ubuntu 11.10 Desktop and Alternate boot CDs, too. For a story of me troubleshooting this problem, check out this thread: http://ubuntuforums.org/showthread.php?t=1942937 Let me know if you need anything else from me, or want me to try anything. I would like to have ACPI working. Thank you. ProblemType: Bug DistroRelease: Ubuntu 11.10 Package: linux-image-3.0.0-18-generic 3.0.0-18.31 ProcVersionSignature: Ubuntu 3.0.0-18.31-generic 3.0.26 Uname: Linux 3.0.0-18-generic x86_64 NonfreeKernelModules: nvidia AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24. ApportVersion: 1.23-0ubuntu4 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC1: paul 1824 F.... pulseaudio /dev/snd/controlC0: paul 1824 F.... pulseaudio CRDA: Error: [Errno 2] No such file or directory Card0.Amixer.info: Card hw:0 'PCH'/'HDA Intel PCH at 0xfa600000 irq 48' Mixer name : 'Realtek ALC889' Components : 'HDA:10ec0889,10ec0889,00100004' Controls : 41 Simple ctrls : 23 Card1.Amixer.info: Card hw:1 'NVidia'/'HDA NVidia at 0xfa080000 irq 17' Mixer name : 'Nvidia GPU 16 HDMI/DP' Components : 'HDA:10de0016,10de0101,00100100' Controls : 16 Simple ctrls : 4 Date: Wed Apr 4 23:20:33 2012 HibernationDevice: RESUME=UUID=671dbf57-276e-4d7e-acda-da8bd954854f InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111011) IwConfig: lo no wireless extensions. eth0 no wireless extensions. eth1 no wireless extensions. MachineType: To be filled by O.E.M. To be filled by O.E.M. ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.0.0-18-generic root=UUID=8cb7655f-2b04-43dc-984c-d395b2f16e23 ro acpi=off quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-3.0.0-18-generic N/A linux-backports-modules-3.0.0-18-generic N/A linux-firmware 1.60.1 RfKill: SourcePackage: linux StagingDrivers: mei UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 10/03/2011 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: 4.6.4 dmi.board.asset.tag: To be filled by O.E.M. dmi.board.name: EVGA E685 dmi.board.vendor: EVGA dmi.board.version: Cougar Point dmi.chassis.asset.tag: To Be Filled By O.E.M. dmi.chassis.type: 3 dmi.chassis.vendor: To Be Filled By O.E.M. dmi.chassis.version: To Be Filled By O.E.M. dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr4.6.4:bd10/03/2011:svnTobefilledbyO.E.M.:pnTobefilledbyO.E.M.:pvrTobefilledbyO.E.M.:rvnEVGA:rnEVGAE685:rvrCougarPoint:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.: dmi.product.name: To be filled by O.E.M. dmi.product.version: To be filled by O.E.M. dmi.sys.vendor: To be filled by O.E.M. 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