A method of performing power down of a computer monitor when a video signal is no longer present and apparatus which performs the method schedules an automatic power conservation mode after a given period of time unless an inhibiting power sustain command embedded in the video signal is received. The power sustain command is placed in the regular video signal at a regular interval. The frequency of the command may be made shorter than the power-off timeout in order to maintain the power-on state of the monitor. Multiple time lapse thresholds may be set to permit multiple power conservation modes. This method may be implemented without making hardware changes in retrofitting a monitor.