I was having trouble with my CPU turning itself on. Previous posts pointed to a CMOS setting under power management,:ModemRingOn/WakeOnLan. So I set this to disable but the problem still persisted. The problem also persisted for others so it was nice to know I was not alone.
Finally discovered another setting under Power Management that needed to be disabled. It was the PME Event Wake Up.
However, when both the above settings were disabled, I got numerous blue screens of death and error messages when booting up. Therefore, had to go back to CMOS and enable ModemRingOn/WakeOnLan.
My computer now stays off when I turn it off.
I hope this helps other people who’ve been having the same problem.