A rack-mountable computer system directs separate portions of a cooling airflow from an inlet air plenum in the computer system interior through separate air passages to remove heat from separate portions of a set of heat-producing components. The air passages can preclude a portion of cooling airflow removing heat from a component from being preheated by another component. Plenums and air passages can be established through the arrangement of components in the interior. Components can be arranged in progressive offsets throughout the depth of the interior to vary plenum flow area throughout the depth, which can progressively impede and redirect airflow through the inlet plenum into the air passages. Arrangements can include an angled row, a staggered configuration, etc. The computer system can include a chassis which can translate, while maintaining operation of hot-pluggable electronic components coupled throughout the depth, to enable swapping of hot-pluggable electronic components throughout the interior.