Abstract: A reverse-return parallel loop system is provided, including a cooling cycle comprised of a plurality of heat sinks, at least one heat exchanger, and at least one liquid pump to carry liquid coolant through the system. Each heat sink has a vapor inlet, a liquid inlet, a vapor outlet, and a liquid outlet. The liquid coolant is pumped into the heat sink through the liquid inlet where the coolant splits in to two streams, where one stream flows out of the liquid outlet towards the next heat sink downstream, and the other stream flows through the heat sink, and through the heat exchanger core to absorb heat from the heat sources and become at least partially vaporized by the heat. This stream then merges with vapor from other heat sinks upstream and flows out through the vapor outlet back towards the heat exchanger of the system.