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How do I troubleshoot random freezes, where the system does not accept any input?

I have a computer that used to run Ubuntu a few years back without any problems (I don't know wether any hardware has changed). Recently, no matter which Linux distribution I install, it will randomly freeze to a point where the cursor is frozen and it doesn't respond to any keyboard input, including alt+sysrq (when the system isn't frozen I can alt+sysrq REISUB and it will reboot). There are no answers in What should I do when Ubuntu freezes? that appear to 'work' in this situation.

I've triggered the freeze with the following systems: Ubuntu 12.04, Ubuntu 14.04, Ubuntu 14.10, Ubuntu 15.04, Ubuntu 15.10, as well as Fedora 22 and 23 (all 64 bit versions). It happens with XFCE, Unity and even Gnome, it happens with nouveau and different versions of the proprietary nvidia driver. It can freeze even as early as during the installation, or during a live session. Sometimes the system will run for 5 minutes before freezing and sometimes two hours. The same hardware can run a Windows operating system for days without issues.

I have tried setting up Kernel Crash Dump, but it doesn't seem to trigger when the system freezes. There are no entries in syslog or kern.log that appear to have been written just before the freeze. On some freezes, the last entry in syslog or kern.log was 30 minutes earlier.

Update: I have disconnected a wireless network card as well as a USB webcam, will let the machine run over night to see if one of those is causing it. Will update with results.

Update 2: It froze again. I'm literally out of ideas. Any suggestions are welcome.

Update3: Some hardware specs that might be relevant:

Motherboard: Sabertooth 990FX R2.0

CPU: AMD FX-8350 Black Edition

GPU: GeForce GTX 660

Update3:

I have recently upgraded the bios of the Sabertooth 990FX R2.0 to Version 2501 (the latest version currently available), without any luck.

Update 4:

I've ran a memtest for 9 hours, several passes and not a single error. There are two DIMMS seated in slot 2 and 4 on the motherboard. I have now tried removing the one from slot 4, and will see if I can reproduce the freeze. Will swap them around afterwards.

Update 5:

It has run for many hours without freezing so far, I'm finding it hard to believe myself. It might be solved, but I don't understand why. I guess I'll try and give it a few days to be sure.

Update 6:

There have been no freezes, and I must conclude that they were caused by faulty memory. Since the memtest didn't show any errors, chances are I would've never figured out what was wrong had I not started disconnecting 'random' parts. Is this the best approach really? If someone can write up a more systematic way to go at something like this, perhaps with troubleshooting from within Ubuntu, I will award them the bounty.

Community
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Tobias
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  • This seems to me like a hardware issue. Did you try unplugging all the external devices? Also check the hard drive for errors and failing. – Gayan Weerakutti Nov 10 '15 at 12:10
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    I haven't tried unplugging everything yet, but how would hard drive errors be causing this when it happens during a live session as well? – Tobias Nov 10 '15 at 12:12
  • Yup my bad. It isn't a hard drive problem then. – Gayan Weerakutti Nov 10 '15 at 12:15
  • Well I just looked at what's plugged in. And the only thing I can unplug is a USB webcam that hasn't been plugged in the whole time. Other than that, there's only a USB keyboard, a USB bluetooth thingy for wireless keyboard, network and hdmi for the monitor. Internally, I could disconnect a wireless network card and multiple storage devices. But should that matter? – Tobias Nov 10 '15 at 12:17
  • I'm not really sure, BTW. – Gayan Weerakutti Nov 10 '15 at 12:20
  • always check for temperature since you are saying this system is already few years old.. – Aizuddin Zali Nov 10 '15 at 13:00
  • The temperatures do go very high when running fancy games, and it will shutdown by itself from too high temperatures - this happens regularly. However, I've monitored the temperatures with psensors a few times when it froze, and the temperatures were fine (20-35 degrees, as opposed to 80 when it shuts down). – Tobias Nov 10 '15 at 13:04
  • How is the GPU Temp? What CPU are you having? – Michael D. Nov 12 '15 at 09:48
  • The GPU temperature is the one that idles at around room temperature, and goes up to 80 when running fancy games - where it shuts down the computer. The CPU is an AMD FX8350 Black Edition. – Tobias Nov 12 '15 at 09:50
  • ...have you tried to update your motherboards bios to the latest version? – Michael D. Nov 12 '15 at 10:55
  • Yes, about a week ago I downloaded the latest bios from their website and installed it. Didn't change anything. – Tobias Nov 12 '15 at 10:58
  • You could run memtest to check for faulty memory. I have observed freezes due to faulty and/or cheap or incompatible memory. If memtest does not find anything try to boot with another working memory DIMM. – antiguru Nov 12 '15 at 15:44
  • @antiguru I guess you could be right, but it would strike me as odd, considering it can run Windows just fine for days at a time. There are two DIMMs in the machine, I'll let memtest run for some hours and if it doesn't find anything, I'll try removing either DIMM. – Tobias Nov 12 '15 at 16:29
  • @Tobias - can this be ? Ubuntu freezes less, when there are less window-managers installed. When only unity is installed then there are less misbehaviours than if when additionally gnome and others are installed. – dschinn1001 Nov 15 '15 at 17:55
  • @dschinn1001, I never installed multiple ones. But I'm pretty sure these freezes were caused by my memory, as I haven't had a single freeze upoen removing one of the DIMMs. – Tobias Nov 17 '15 at 08:04
  • Random freezes are difficult to impossible to solve. See http://www.chiark.greenend.org.uk/~sgtatham/bugs.html . IMO the most common causes are - poor quality or buggy drivers, video and wireless are most common, over heating, hardware problems, either hard drive or RAM are most common, and problems with suspend/hibernation. Work through the list, disable wireless, disable hibernation, etc and see if you can isolate the problem further. – Panther Nov 17 '15 at 17:33
  • @Tobias - for nvidia there are several solutions out here, I had mine own solution (more topologically non-popular solution). When you search through my profile you can find the nvidia-solution there. On my machine there were no freezings. – dschinn1001 Dec 04 '15 at 23:15
  • Copy Update 6 to an answer, and set it as solution please. – davidbaumann Dec 07 '15 at 18:53
  • @davidbaumann - what you mean, or did you mean somebody else ? – dschinn1001 Dec 18 '15 at 20:45
  • You can create a solution for your own anser, so others can find it later. – davidbaumann Dec 18 '15 at 22:12

1 Answers1

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Here is what works for me .

Whenever Ubuntu freezes and no keyboard or mouse input works for me I launch a fullscreen login terminal ( I don't know the proper name) by pressing Ctrl+Alt+F1.

After the terminal is launched I again press Ctrl+Alt+F7. And it brings me back to my original GUI Ubuntu working environment.

And Ubuntu unfreezes.

Additional Info

After launching that terminal you can logout or restart or do whatever you want to do in a traditional terminal.

You can use any of the buttons F1 to F6 using the combination above to launch the terminals. And can launch the GUI environment using F7 as described above.

Sayan Bhattacharjee
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  • I'm sorry but I think you misunderstood the question. When I say that keyboard and mouse input doesn't work, that includes the Ctrl+Alt+F1 keypress. Alt+sysrq is usually the next thing to try, and that is why it is mentioned in the title rather than 'Ctrl+Alt+F1'. – Tobias Dec 23 '15 at 12:29