A power management system and interface providing a flexible and uniform protocol for controlling power management within a computer system including various software layers and add-in components. Clients (registered system elements) requiring power management notification and control become registered (via an associated software component) with a power management coordinator (PMC). The PMC provides information routing functions and address translations to facilitate communication (including power consumption information) between clients at registered identifiers. A programmable power policy manager allows a user to define a performance/economy setting for the system that is communicated to all registered devices so that dwell and decay times are appropriately set by the device. A programmable event sequencer maintains an event notification sequence and control sequence for power events. A programmable power budgeter maintains and allocates power on a request basis for system elements. A programmable thermal budgeter maintains and allocates energy based on thermal considerations. A BIOS interlace couples for communication between an APM BIOS (if present) to send commands and poll for and receive event notification. Registered extensions may be used to provide alternate functionality for the sequencer, the power policy manager, and the thermal and power budgeters. The PMC provides for communication of power status, events, and other information between registered devices and allows registered software applications to originate power events. Other extensions may register to enhance power management.