1- The machines have no relation with the operating systems, it turns out that the old machines were different, as technology advances, everything will be smaller and more efficient. And who determines this are the manufacturers, not the system.
2-Generally, problems with date and time, or region, can lead to believe that the CMOS battery needs to be replaced, since it is responsible for storing data while the PC is turned off.
3-If you do not have experience, it is not recommended to change the CMOS battery at home, but take it to a local technical assistance.
Yours sincerely,
Claudeir