A power supply system is operable to contemporaneously supply power to multiple output ports when available power from a power source is insufficient to meet maximum potential power requirements of load devices coupled to the output ports. The power supply system includes a system monitor, multiple power converters, and optional temperature sensing circuits, where each power converter supplies power to a respective output port. The system monitor monitors an output power characteristic of the power source, output powers delivered to the output ports, and/or temperatures detected by the temperature sensing circuits. When the system monitor detects an overload condition is approaching based on the monitored parameter or parameters, the system monitor generates control signals which cause the power converters to maintain or reduce their output powers such that the overload condition is abated and two or more output ports continue to deliver output power to their respective load devices.