We have a HP Proliant ML110 G6 server running (Windows 2012 Server R2) which is giving problem since last few days. The problem is that it restarts automatically and randomly. By restart I mean to say, it reboots automatically while running. We are unable to figure out the cause. There is no fixed time for reboot. Sometimes, it works for a few hours before reboot and sometimes it lasts only a few minutes. Could it be an issue with power-supply that stops giving power after some time? Do you have any directions that we need to look into?
Does the system have an iLO meta computer? Look in all iLO event logs, there should be a message indicating that iLO thought the Operating System had "locked up" and so the hardware needed to be reset.
In the BIOS settings turn off all WatchDog timer features, otherwise known as Automatic Server Recovery or ASR. A WatchDog timer in the baseboard management controller monitors a timer reset by the operating system every so many seconds. If the operating system allows the timer to expire, ASR kicks in and electronically resets the system.
In Event Viewer, look for Event ID 100 under Microsoft-Windows-Diagnostics-Performance to identify when the server started. Then look the events preceding that in System/Application logs to maybe find out why it rebooted.
If you can't find anything, try to run a complete system diagnostic from the BIOS (memory, CPU, etc) and check the iLO logs (as suggested by Chopper3).