Modular data center without active cooling

A modular computing system for a data center includes one or more data center modules including rack computer systems. An electrical module is coupled to the data center modules and provides electrical power to computer systems in the data center modules. The data center modules do not include any internal active cooling systems and cannot be coupled with any external active cooling systems. A data center module directs ambient air to flow into intake air plenums extending along intake sides of the rows of racks, through the rows of racks into exhaust plenums extending along exhaust sides of the rows of racks, and out into the ambient environment to cool computer systems in the racks. Directed airflow can be lateral, vertical, at least partially driven by air buoyancy gradients, at least partially induced by air moving devices internal to computer systems in the rows of racks, thereof, etc.