A housing with improved airflow is provided. The housing includes a cage dimensioned to hold two modules side-by-side in a lower compartment and a further two modules side-by-side in an upper compartment. The cage has a middle compartment between the lower compartment and the upper compartment, with a heatsink in the middle compartment in thermal contact with the two modules when the two modules are in the lower compartment. The middle compartment is ventilated through a first one or more apertures in each of two or more exterior walls of the cage, the middle compartment is further ventilated, when the upper compartment is unoccupied, through a second one or more apertures in an interior wall of the cage separating the middle compartment and the upper compartment, wherein the further two modules when occupying the upper compartment obstruct the second one or more apertures.