Some DMMs display a higher voltage if the battery goes flat.
Do you have a low battery warning on the LCD?
yaoyaoh:
The reason why I need 5V is to power an external DAC which needs exact 5 volt.
The Due uses a switching (buck) 5volt supply when on external power.
Seems a bad idea to power a DAC from a potentially dirty supply.
Make sure the DAC doesn't mind the 3.3volt logic.
Leo..