A power management method and mechanism for dynamically determining which of a plurality of blocks of an electrical device may be powered on or off. A device is contemplated which includes one or more power manageable groups. A power management unit associated with the apparatus is configured to detect instructions which are scheduled for execution, identify particular power group(s) which may be required for execution of the instruction, and convey an indication which prevents the particular power group(s) from entering a powered off state, in response to detecting said instruction. If the power management unit does not detect an incoming or pending instructions, for a predetermined period of time, which requires a particular power group(s) for execution, the power management unit may convey an indication which causes or permits the corresponding power group(s) to enter a powered off state. A power group may automatically decay to a powered off state in the absence of a detected instruction requiring the power group. Instructions may be encoded to identify required power groups.