A power management controller (PMC) that interfaces with a processor comprising one or more cores. The PMC may be configured to communicate with each respective core, such that microcode executed by the respective processor core may recognize when a request is made to transition the respective core to a target power-state. For each respective core, the state monitor may monitor active-state residency, non-active-state residency, Direct Memory Access (DMA) transfer activity associated with the respective core, Input/Output (I/O) processes associated with the respective core, and the value of a timer-tick (TT) interval associated with the respective core. The status monitor may derive respective status information for the respective core based on the monitoring and indicate whether the respective core should be allowed to transition to the corresponding target power-state. The PMC may transition the respective processor core to the corresponding target power-state accordingly.