Avelino Tavares wrote:
I change the power supply with a new one, but the problem continue,
And what about if i update the bios for the last one ? It could result ??

A wake on LAN setting is another possible cause of a computer starting
on its own. Disconnect the LAN cable, then do a shutdown. Does
the computer now remain off ?

One Wake On LAN (WOL) feature, is effectively Wake On Activity. Which
means, the computer awakes, as soon as there is any activity on the
LAN port. You can try examining the properties of the LAN device in
Windows, and see what WOL options are offered, and "disable" the feature
to see if it makes a difference.

Paul