Power management for clusters of computers, a cluster including a configuration of computers operating in a power management domain, one or more of the computers of the cluster having a power requirement that differs from power requirements of other computers in the cluster, data processing operations on the cluster effecting a processing load on the computers in the cluster, including selecting, from a plurality of configurations of computers capable of supporting a plurality of processing loads at a plurality of power levels, a configuration of computers capable of supporting the processing load at a lowest power level, the lowest power level defined by comparison among configurations capable of supporting the processing load; and reconfiguring the cluster according to the selected configuration.