Adrian Caspersz wrote:

Dave Plowman wrote:

It fired up and selected the BOIS page. But on configuring, saving and
exit, back to not firing up at all.
So looks like an MB failure?

Common fault. Your BIOS 'CMOS' memory settings are corrupt.

I had a similar sounding issue with two different ASUS models a few
years ago, some sort of optimal memory speed setting would kick in, then
at next boot it would think the setting wasn't right, so revert the
setting, power itself off, and power back on aft a few seconds with the
"safe" setting, but it seemed to get stuck in a loop ...