A power management unit (PMU) may promote a processing core from a working state to a first non-working power saving state after receiving a signal from an automatic core C-state promotion (ACCP) unit. An OS component may detect the idling of the processing core and may initiate the ACCP. The ACCP may initiate the PMU to promote the processing core to a first non-working power saving state. The ACCP may track the residency time of the processing core in the first non-working power saving state and may initiate the PMU to promote the processing core to a next non-working power saving state if residency time of the processing core in the first non-working power saving state exceeds a first value. The ACCP may initiate the PMU to demote the processing core back to the working state if a break event occurs during the residency time.