in a computer system that includes processing , memory and i / o modules and acpi for outputting an onctl signal to a power supply unit . the power supply is configured to output a power off signal indicative of power off state and power on signal indicative of power on state . there is provided an embedded controller coupled to the acpi and to the power supply unit . the embedded controller includes input for receiving a shut off event and in response to the shut off event , feeding to the acpi a controller power off signal as long as the power supply is in power on state .