A reliable, leak-tolerant liquid cooling system with a backup air-cooling system for computers is provided. The system may use a vacuum pump and a liquid pump and/or an air compressor in combination to provide negative fluid pressure so that liquid does not leak out of the system near electrical components. Alternatively, the system can use a single vacuum pump and a valve assembly to circulate coolant. The system distributes flow and pressure with a series of pressure regulating valves so that an array of computers can be serviced by a single cooling system. A connector system is provided to automatically evacuate the liquid from the heat exchangers before they are disconnected. Leah detection and mitigation structures are also disclosed. Various turbulators are also provided, as well as a system and method for optimizing the heat transfer characteristics of a heat exchanger to minimize total energy requirements.