A computer system that selectively disables power to wake on LAN (WOL) devices in the absence of AC power. In one embodiment, the computer system comprises a power supply and a power management controller. The power supply is configured to provide power to a wakeup device. The power management controller receives an AC voltage sense signal that indicates the presence or absence of an AC power source and enables the power supply to provide power to the wakeup device when the AC voltage sense signal is asserted. The power management controller preferably disables the power supply when the AC voltage sense signal is de-asserted. The computer system may operate in several states including an off state, a power on self test (POST) state, a working state, a trap state, and an armed state.