when I say a clean install what I actually mean is that the HD on the system is only used for software all info is kept on a number of external drives or my NAS.
So since purchase the OS has gradually been upgraded form vista, through Xp, to w7, W8, and recently to W10.
Crossed wires as a clean install implies that certain software has been uninstalled and reinstalled afresh, in this instance it appeared that you had done a clean install of Windows 10 and that was why I asked about the RAID drivers, by the by now you have explained.
Very surprised that the computer worked with Windows 10 at all tbh being that there are no Windows 7 drivers let alone drivers for Windows 10.
At the same time as replacing the PSU I checked for a bios update and reflashed to A07, and then an install of office2016.
Since then all has been great,
How long was the computer running fine for and did the computer shut down and reboot without issue on more than one occasion after flashing the BIOS.
Is the HDD detected in the BIOS, a Seagate HDD will begin with the letters ST and a Western Digital HDD will begin with WD, other brands vary and please note that any mention of a HDD in the Boot sequence that is not labelled with such letters is only the boot order and not the BIOS detecting the presence of a working HDD.