I have had exactly the same issue since new - currently investigating with support but nothing useful forthcoming so far, bios and chipset etc all updated.
It happens seemingly completely randomly, sometimes every couple of days, sometimes two weeks can go by without it.
There is nothing in the event logs or bios diagnostics.
I have recorded each time it has happened and what the system was doing at the time, there doesn't seem to be any pattern at all. Sometimes lid is closed, sometimes not, sometimes plugged in, sometimes on battery, sometimes a few minutes after boot up sometimes after 8 hours use. I'm not running anything too taxing.
It's very loud and very annoying.....
