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 exchanger ; 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 ; wherein the coolant-to-coolant heat exchanger is arranged downstream of the door heat exchanger with respect to the first coolant flow as the first coolant flow travels through the electronics cabinet . 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 exchanger ; 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 ; wherein the coolant-to-coolant heat exchanger is arranged downstream of the door heat exchanger with respect to the first coolant flow as the first coolant flow travels through the electronics cabinet . <EOS>