A system and method are provided that comprise a circuit board including one or more processors and a chassis that holds the circuit board. The chassis includes a card receptacle that receives an electronics card. The electronics card comprises a card circuit board having electronic components including one or more processors. The card circuit board has a chassis loading end. A heat sink is provided on the circuit board and thermally coupled to one or more electronic components to dissipate heat therefrom. The heat sink has a three-dimensional envelope having a stepped end profile relative to the chassis loading end. Vent openings are provided in shielding of the electronics card for airflow from the electronics card.