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 in combination to provide negative fluid pressure so that liquid does not leak out of the system near electrical components. 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. The system provides both air and liquid cooling so that if the liquid cooling system does not provide adequate cooling, the air cooling system will be automatically activated. A connector system is provided to automatically evacuate the liquid from the heat exchangers before they are disconnected.