A multi-rack assembly that includes adjacent first and second electronics racks, each of which is at least partially air-cooled, and an air / liquid heat exchanger, which is associated with the first electronic rack for cooling at least a portion of the air which moves through the first rack passes, are provided. The heat exchanger, which is arranged on the air intake side or the air outlet side of the first rack and is connected to a coolant loop in fluid communication to receive coolant from the loop and to deliver coolant to the loop transfers heat from the air that moves across him to which coolant moves through it. The assembly also includes a cooling unit associated with the first rack and cools the coolant in the coolant loop, and an air flow guide, which is associated with the second rack and allows, that at least part of the air which moves through the second rack through is passed so that it moves further away via the heat exchanger, which is associated with the first rack ,.