A data processing system and method are described for controlling power supplied to the system. The system includes an internal power supply for receiving energy from an external source and supplying the energy to the system. The energy is full system power and is required for the system to be fully operable. The system is initially powered-off such that the energy is not initially supplied to the system. A power-on password is established. The internal power supply supplies the energy to the system only in response to a correct entry of the power-on password, wherein the system is inoperable prior to the correct entry of the power-on password.