An apparatus for, and method of, providing a desired temperature-differential circuit card environment includes a plurality of card units. Each card unit comprises a first thermal plate having front and back first plate sides oriented in a lateral-longitudinal plane, the first thermal plate operating at a first plate temperature. A second thermal plate has front and back second plate sides oriented in the lateral-longitudinal plane, the second thermal plate operating at a second plate temperature. A coupler is oriented in the lateral-longitudinal plane and is connected to front and/or back first plate sides and to the front and/or back second plate sides to form a card unit. The card units are arranged in a transversely oriented stack with the front first and second plate sides of a second card unit being directly transversely adjacent the back first and second plate sides of the first card unit.