Aspects of an embodiment of the invention disclose a method, computer program product, and system for managing the energy efficiency of servers providing multi-class computing services with Quality of Service (QoS) assurance. Computing resources are clustered into at least three groups, where each group has a separate power management policy (PMP). A plurality of requests are received from a plurality of devices, and are sorted into at least three service classes based on the requests' QoS criteria. Each request is assigned to one of at least three service queues based on the request's service class, and each service group is processed by a group of computing resources. The power management policies are configured such that each group of computing resources may service requests at an energy efficient point while meeting the QoS criteria of the service class.