A novel electronics cooling method and system is disclosed. A very flexible and efficient operation of an electronics cooling system (10) is achieved by controlling circulation of a cooling medium in a closed system (40) containing an evaporator (13), a condenser (14), an ejector (11) and control valves (15 18). Specifically, the system is continuously allowed to operate in the most appropriate mode by controlling the valves (15 18) of the system (10) based on detected heat load and/or detected heat transfer conditions. By automatically adapting the mode of operation of the system based on the actual prevailing conditions, a unique flexibility is obtained with regard to the cooling mode in which the system will be operated. This means that the cooling capacity will be constantly optimized and that the investment cost as well as the cost for operating the system will be reduced compared to known systems having equal maximum cooling capacity.