As much as I don't want to re-suggest what I did last time with the previous card, I agree that OC is suspicious because overclocking can cause problems. Like before, it can be configured in Afterburner.

You could try searching in the Windows search box: event viewer

Open it, then click Windows Logs, then click System and look at the recent errors (especially any Red ones or any that happened at the Timestamp that it shut down). The errors don't make sense ever, so don't worry about that, but they can sometimes provide a hint such as mentioning the type of fault that shut it down, or an error code that you can google.

You could also look at Application in case it is an application issue, but it'll help to see if there is a system issue first.