A method of reducing power consumption of a Radio Network Controller with a plurality of control units in a wireless communication system, each of the control units including one or more processors, the control units being adapted to operate in an active mode or adopt a power saving mode and a first control unit i operating in the active mode, the method comprising the steps of measuring a degree of utilization Cwi of the first control unit i, comparing the degree of utilization Cwi of the first control unit i with a first threshold Tsli, and changing the mode of the first control unit i to a power saving mode after a predetermined first period of time if the degree of utilization of the first control unit i is below the first threshold Tsli.