I started getting random reboots a few months ago. Sometimes it happens minutes after boot. Sometimes it takes 2 weeks. Server had been running for several years prior without issue. I have added some HDD disks, and a PCIe NIC.

When it happens it reboots immediately.

I ran a remote syslog server to capture errors before the crash but I don't see any. Do you?

Memtest86 ran for 8 passes no issue.

Any ideas where to look next?


Thanks.

tower-diagnostics-20251212-1624.zip syslog

Random reboots are almost always hardware-related, or bad power.

Any ideas on where to begin?

You don't see anything weird in the logs?

12 hours ago, JorgeB said:

Random reboots are almost always hardware-related, or bad power.

Because memtest is only definitive if it finds errors, if you have multiple sticks try using the server with just one, if the same try with a different one, that will basically rule out bad RAM.

After checking for bad RAM as @JorgeB suggested, I would look at replacing the Power Supply next. PS are not just a simple brick with a transformer, rectifier and some voltage regulators any more. They are connected to and interact with the MB. (A few years back I upgraded a PS and the server started doing exactly what you server is doing. Replaced that new PS and have never had another unexpected reboot!)

On 12/12/2025 at 10:37 PM, adminmat said:

When it happens it reboots immediately.

Sounds like a "hanging" Reset- or Power-Button maybe?

Edited December 14, 2025Dec 14 by Zonediver

4 hours ago, Zonediver said:

Sounds like a "hanging" Reset- or Power-Button maybe?

I seem to remember a number of years ago when one Unraid user's server was being rebooted by his pet cat. The animal apparently was attached by the blue LED behind the switch and would 'bat' at it. (Young kids are another possibility...)