A cooling system for the electronic components of a computer rack, including a primary circuit of primary liquid; a primary exchanger intended to transfer heat from first electronic components to the primary liquid; a secondary circuit of refrigerant fluid; a primary-secondary exchanger; a tertiary circuit of tertiary liquid; a secondary-tertiary exchanger; and a tertiary-thermal source exchanger. The cooling system also includes a tertiary-secondary exchanger; and an air-tertiary exchanger intended to transfer, to the tertiary liquid, heat from the air of the computer rack heated by second electronic components, the air-tertiary exchanger being arranged, in the tertiary circuit, downstream of the tertiary-secondary exchanger and upstream of the secondary-tertiary exchanger.