I am running a Intel XEON 1245 with 4GBx2 Kingston Memory ECC Unbuffered DDR3 on an ASUS P8B WS motherboard. BIOS Version 0904 x64. This system is a little over a month old. It is running Ubuntu 11.10.

This evening I found the machine turned off. When I tried to restart it, it would POST and stop at the GRUB screen. When I selected Ubuntu and hit enter within 2-3 seconds the would shutdown and restart. If I stayed at the GRUB screen and did nothing the system would not cut out.

I tried booting off a USB stick and again 2-3 seconds after selecting 'Try Ubuntu without Installing' the machine will cut power and reboot.

Things I have tried so far:

• Resetting the BIOS using the on board jumper
• Resetting the BIOS settings to default
• Disconnecting all external hardware - except keyboard & monitor
• Booting with 1 stick of RAM - I tried different single sticks
• Ensured that onboard EPU and GPU boost switches are in the off position.

I am running a Memtest86 right now and it has been running for 38+ minutes. This is not an OS problem or an overheating issue (I have a CoolerMaster HAF Case with 3 fans besides the CPU fan)

I am at a loss as to what to try next. I think the BIOS is mis-configured somehow but I don't know what to look for.