Ubuntu Gnome 16.04 Sporadically Spontaneously Reboots on Custom Built Machine

What happens...

I will be working along and the computer goes through a spontaneous reboot. Usually the reboot is without warning, but sometime there are clues that is it coming like a frozen keyboard or the mouse not acting correctly.

What I have done...

  • Verified operating system and all software is up to date. (The OS is regularly updated automatically.)
  • Updated motherboard firmware.
  • Ran Memtest86 over the weekend to test RAM without error.
  • Ran Primes95 overnight to stress test the CPU. No problems.
  • Swapped out drive. Same issue even with clean install of the operating system.
  • The hardware has all been reseated.
  • I did discover that the CPU was running hot (70℃) and increased the cooling. Manufactor specs say 61℃ tops.
  • Tried. Tried to read various logs in the /var/log. (I you would like to see them, I will be glad to post recent one with crash and reboot times.

Tidbits that may be "red herring" or may be clues...

  • My other Gnome Ubuntu machines (with different hardware specs) built with the same software profile are NOT having the same problem.
  • The first time I saw these reboots, it was when I was using ScreenConnect with depends on Java
  • Since then I have seen it happen when I am browsing using FireFox
  • I have seen it occasionally when I am using LibreOffice
  • The other night it rebooted itself when the only thing running was Backup
  • After it goes through the crash and reboot cycle and logging back in, trying to use Super Key + "Type to search" to find an application is almost a guarantee to create another crash and reboot. It will usually crash and reboot when the second letter is typed.
  • Sometime it will automatically reboot again during the reboot after the initial crash and reboot. The reason I know this is because I have to enter disk encryption password again.
  • Sometime one of the monitors does not start after the reboot. If the computer is shutdown when this is happening, sometimes the monitor is not turned off either.
  • After a cold start - where the machine has been shut off for the night - it will usually behave itself for a couple of hours.
  • Frequency of crash is increasing.

Here are the hardware components...

  • CORSAIR RM Series RM650 650W ATX12V v2.31 and EPS 2.92 80 PLUS GOLD Certified Full Modular Active PFC Power Supply
  • ASUS M5A97 LE AM3+ AMD 970 + SB950 6 X SATA 6
  • G.SKILL Sniper Series 16GB (2 x 8GB) 240-Pin DDR3 SDRAM DDR3 1866 (PC3 14900) Desktop Memory Model F3-1866C9D-16GSR
  • AMD FX-8370 Vishera 8-Core 4.0GHz (4.3GHz Turbo) Socket AM3+ 125W FD8370FRHKBOX Desktop Processor
  • Corsair Hydro Series H55 Quiet Edition Liquid CPU Cooler (CW-9060010-WW)
  • Cooler Master Rifle Bearing 80mm Silent Cooling Fan
  • SAMSUNG 840 EVO MZ-7TE250BW 2.5" 250GB SATA 6Gb/s 1x nm Samsung Toggle DDR 2.0 3-Bit MLC NAND Flash Memory (400Mbps) Internal Solid State Drive (SSD)
  • AMD FirePro W4100 100-505817 2 GB 128-bit
  • Cable Matters Gold Plated Mini DisplayPort to HDMI
  • Dual ASUS PB287Q 4k UHD LED Monitor
  • CODE 104-Key Mechanical Keyboard - Cherry MX Brown
  • Logitech Wireless Marathon Mouse M705
  • Logitech T650 Rechargeable Touchpad with Windows 8 Multi-Touch Navigation
  • Penguin USB Bluetooth 4.0 Micro Adapter
  • Penguin Wireless N PCI Card v5
  • Plantronics BT300 USB Bluetooth Adapter Dongle 85117-02 PL-BT300
  • Plantronics Voyager HD Headset

Here is the software list...

  • Ubuntu Gnome 16.04 LTS
  • Dia
  • Dropbox
  • Flash Player Browser Plugin
  • FreeFileSync
  • IcedTea Plugin
  • Inkscape
  • Java Run Time
  • Keepass
  • Linphone
  • Mono - mono-complete
  • Mount NFS Shares - nfs-kernel-server
  • PDF Printer (with an adjust outputed folder and apt-armor)
  • rDeskTop
  • SimpleScreenRecorder
  • SpeedCrunch
  • Thunderbird
  • VirtualBox
  • Wide Margins Bible
  • Windows Manager - wmctrl
  • FireFox Tweaks...
    • KeeFox
    • AdBlock Plus
    • BetterPrivacy
    • Blur
    • Clean Links
    • Cleanest Addon Manager
    • DownThemAll
    • Element Hiding Helper for AdBlock Plus
    • FoxyProxy Standard
    • ScrapBook X
    • Self-Destructing Cookies
    • Session Manager
    • Snap Links Plus

Links I have read without finding the solution...

Is there other testing or things to look narrow down the problem before just swapping out hardware? If there is not, what hardware would you recommend starting with?


The executive answer: Bad grounding in office electrical system.

After systematically changing out ALL the hardware and still having the same problem, I started to get suspicious of something upstream in the electrical network. Tracked it down a missing ground connection. Fixed that, put all my parts together, and now have two working computers. And a busted budget.

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