1. A method of cooling an electronics cabinet, comprising:inducing a flow of cooling air to enter into an electronics cabinet at a first temperature;
passing the flow of cooling air over a plurality of electronic modules arranged within the electronics cabinet to convectively transfer heat to the flow of cooling air from the plurality of electronic modules at a first heat transfer rate;
directing the flow of cooling air through a door heat exchanger arranged at an end of the electronics cabinet to exhaust the flow of cooling air from the electronics cabinet at a second temperature;
receiving a first coolant flow into the electronics cabinet;
directing the first coolant flow through the door heat exchanger;
transferring heat from the flow of cooling air to the first coolant flow at a second heat transfer rate as the flow of cooling air and the first coolant flow both pass through the door heat exchanger;
directing the first coolant flow through a coolant-to-coolant heat exchanger arranged within the electronics cabinet;
circulating a second coolant flow through a coolant loop arranged within the electronics cabinet, the coolant-to-coolant heat exchanger being located along said coolant loop;
passing the second coolant flow through a plurality of cold plates joined to at least some of the plurality of electronic modules to transfer heat therefrom to the second coolant flow at a third heat transfer rate;
transferring heat from the second coolant flow to the first coolant flow at a fourth heat transfer rate as the first and second coolant flows both pass through the coolant-to-coolant heat exchangers;
removing the first coolant flow from the electronics cabinet; and
rejecting heat from the first coolant flow at a location remote from the electronics cabinet.