An apparatus includes voltage summation logic to provide a summed voltage corresponding to a sum of voltage contributions, each contribution associated with a corresponding port controller of a plurality of port controllers. The apparatus also includes a first port controller to determine, based on the summed voltage, whether a second power source is to be coupled to a system power bus of a system via a second port controller of the plurality of port controllers, and if not, the first port controller is to couple a first power source to the system power bus. Other embodiments are described and claimed.