A method of and apparatus for cooling heat-generating devices in a cooling system is disclosed. The apparatus includes various sensors, control schemes and thermal models, to control pump flow rates and fan flow rates to minimize power consumption, fan noise, and noise transients. The apparatus further includes at least one heat-generating device, at least one heat exchanger, and at least one heat rejector. The apparatus can also include many pumps and fans. The method includes controlling a fluid flow rate of at least one pump and an air flow rate of at least one fan, in a cooling system for cooling at least one device. The method comprises the steps of: providing at least one temperature sensor coupled to measure a temperature value of each device; receiving the temperature value from each temperature sensor; and providing a controller to selectively control the fluid flow rate and the air flow rate, based on each temperature value. The method can further include the step of filling at least a portion of a heat exchanger with a thermal capacitance medium for maintaining the temperature value of the device below a maximum allowable temperature during thermal transients, wherein the heat exchanger is thermally coupled to the device.