A cooling system is provided employing at least two modular cooling units (MCUs). Each MCU is capable of providing system coolant to multiple electronics subsystems to be cooled, and each includes a heat exchanger, a first cooling loop with at least one control valve, and a second cooling loop. The first cooling loop receives chilled facility coolant from a source and passes at least a portion thereof through the heat exchanger, with the portion being controlled by the at least one control valve. The second cooling loop provides cooled system coolant to the multiple electronics subsystems, and expels heat in the heat exchanger from the multiple electronics subsystems to the chilled facility coolant in the first cooling loop. The at least one control valve allows regulation of facility coolant flow through the heat exchanger, thereby allowing control of temperature of system coolant in the second cooling loop.