Analytical evidence and experimental results suggest that return air temperature control limits the effectiveness and efficiency of data center cooling. Return air temperature control rarely, and often only coincidentally, enables a close match of air provisioning relative to IT equipment consumption. Other methods that divorce the flow control from the temperature control offer much better opportunities to tune cooling performance, either manually or automatically, producing improvements in operational energy and capital usage. Under-floor static pressure control is one such method. This paper presents evidence that suggests that static pressure control is a viable and often superior alternative to return air temperature control.