Well, since I disabled and re-enabled my SLI it hasn't happened once... Nvidia CP is now on prefer maximum performance and there is no issues.

Yeh, I have been playing the old Brothers in Arms games recently, RO2 and the first COH. I love WWII as a setting. I'd like to see one focused on the British.

The X Files

Battlestar Galactica

Farscape

@zaku101: That setting was already on. I guess it was because my PC was on the high performance power setting. So it has been happening while that setting is on, not really any way to judge by that.

@zaku101: Would disabling SLI stopping it from happening suggest it is my PSU. causing the problem? I disabled SLI through Nvidia CP and it hasn't happened since then.

I will also try your suggestion. If it is my PSU it will not be too bad as I have been wanting to go full modular for a while to improve wire management in my case.

@Yams1980: Updates usually do the shutting down process though, not just switch off the PC.

@zaku101: A full restart.

@Yams1980: I have Windows 10 and it has only been installed in the last few months. It has been working fine since a few days ago though. I don't think it is my OS.

I am wondering whether to get a new PSU, but it doesn't really make sense if it shuts down when idle and it doesn't always happen while at 100% load for a decent period.

Using the Prime95 blend test my processor reached 80-85C on different cores.

GPUs were at around 60C on the Furmark stress test.

No shut downs of my PC, though.

Another thing to add, it doesn't seem to happen just when I am gaming. It has a few times but only at the same regularity as other times it has happened. Nor does it become more frequent when I am gaming. Which is weird as that is when I thought it would occur more if it was a power supply or overheating issue.