T3620 frequent 'power off' issue

Hi,

I have a precision 3620 which keeps powering off, just as if someone pulled the plug out of the back.

Bios up to date. Drivers up to date. Nothing in event logs apart from "unexpected shutdown" when it powers back up.

Tried a couple of completely fresh windows 10 reinstalls on 2 different SSDs. Issue is still there on both..

Machine was working fine yesterday until I decided to 'freshen it up' by doing a re-install. (Reset failed, before anyone asks - hence reinstalls).

Kind of stuck on where to look to solve this issue, as I have nothing to go on..

Any ideas / suggestions on what might be the cause?

Thanks,

D.