That PSU sounds good enough to me.
Could be worth a motherboard firmware update?
and i would double check all the power cables.
It looks ike mangohud is an application to monitor stuff. I've never used it but you could give that a go - see if you're ever getting close to the 750W.
I don't get it. If you have a pile of gold and there are no other people involved, how does its value change?