2

I have a Windows 7 Pro x64 system (i7 if it matters) that randomly restarts.

This system is required to be online all the time, but it restarts in a very random way. I can go 5 days without a random restart, but other times it will restart 3 times within a 6 hour period, the shortest time between restarts I have observed being about 1 hour.

No error message, no popups, no blue screen, no event logs under "system" or "application". It's connected to a UPS, the UPS logs indicate zero power events.

In the system logs all I see is information regarding the recovery from an unexpected shutdown, but no error messages or events directly previous.

Originally I was set to do kernel dumps, but since I never generated any dump files from these restarts I thought I'd try the mini-dump, which also yielded no dump files.

What tools can I use to diagnose what is going on?

EDIT (to address comments): We have performed a power analysis on the system. The PC is fed with a 24V supply, and all power lines between the PC/UPS/Supply have been tested for robustness and accurate power levels.

The PC is in an air-conditioned enclosure kept at 20 degrees Celsius. Bios indicates that the PC is running relatively cool, each core runs somewhere around 40 degrees Celsius, which gives me a lot of room before Tmax.

I have tested the UPS by removing main power from the system and watching the UPS wait the 30-second grace period before performing a controlled shutdown on the system.

The system in question and all the associated power supply and UPS hardware are relatively new, perhaps 4 months old.

The BIOS is using the latest revision.

I will try to remove the UPS from the equation to see if there's an issue with current overage, but since this was never an issue when tested I am not sure this will change much.

5
  • 3
    Eliminate possible causes. UPS, Power Supply, Memory, HDD, CPU, all of those could cause a hardware fault that the kernel wouldn't be able to detect and thus generate a event/error for.
    – Ramhound
    Jun 11, 2015 at 15:27
  • 1
    Generally speaking, Black screen shutdowns are caused by power or thermal considerations. Monitoring at the UPS level wouldn't show if you demanded more power than the power supply could provide, and would result in a blackscreen reboot. likewise, if the CPU hits its Tmax it will shut down the system without letting the OS know. Jun 11, 2015 at 15:29
  • Get the model of your motherboard and check online for a BIOS update. If one or multiple are available then read through the changelog to see what the new releases fixed. If an entry says Fixed issue where a reboot occurs if L3 cache miss is etc, etc... then I would opt to apply the update.
    – MonkeyZeus
    Jun 11, 2015 at 15:38
  • 1
    A UPS with a dead battery often exhibits this behavior - power to the connected system dies instantly anytime an attempt is made to switch to battery power. Since brownouts/surges/tests will make it try the attached system will go down a lot. Test the UPS to see if it holds up under battery power and if it doesn't replace the battery.
    – Brian
    Jun 11, 2015 at 15:48
  • I've added an edit to address the comments. @Ramhound how can I test those items individually? This is a fully integrated PC, and I am unable to swap out the CPU or Memory. Jun 12, 2015 at 13:12

0

You must log in to answer this question.

Browse other questions tagged .