A method of operating a system on chip (SoC) includes determining to switch from a selected low-power core among a plurality of low-power cores to a high-performance core among a plurality of high-performance cores, counting the number of high-performance cores that are operating among a plurality of high-performance cores, determining a maximum operating frequency of the plurality of high-performance cores based on the counted number, and switching from the selected low-power core to the selected high-performance core based on the determined maximum operating frequency.