.. but the shutdown issue hasn’t come back.
While the hard drives were being CHKDSK’ed on other machines, I had my tower up on the desk and gave it a thorough cleaning. And no, it wasn’t because the machine was overheating. I often clean out the case, so this task was not unusual.
While executing the above, I made a note of the motherboard serial number which is located on the side of the incoming 24 pin power socket. In order to read it, I had to remove the DVD drive and a mass of wiring associated with the DVD drive, the case’s X-Port, and the four case fans.
So, while connecting everything, I noticed that I hadn’t been utilising one of the cables from the power supply. Hamm, could it be that there was too much loading on one cable? I am now using both cables which terminate in the standard Molex ends, spreading the load across both.
Oh, and I have put back the third hard drive. The only piece missing is the card reader which I let go because it originally came out of a computer which had suffered a big power surge.
If, in the next few days, it starts to shutdown again, I will be surprised but ready to RMA the mobo. For now, I have my fingers crossed..