A DRS cluster can be configured to change the power state of the selected hosts in order to reduce the power consumption by the cluster. This feature is called vSphere Distributed Power Management and is configurable only if the cluster is DRS-enabled.
vSphere DPM uses IPMI for power management. Hence, for the ESXi hosts to be managed by DPM, they have to be configured with their corresponding IPMI settings. This has to be done at a per-ESXi host level under Manage | Settings | Power Management.
The following procedure will help you enable and configure DPM on a DRS-enabled cluster:
From the vCenter's inventory home, navigate to the Hosts and Clusters view.
Select the cluster, navigate to Manage | Settings | vSphere DRS, and click on Edit.
On the Edit Cluster Settings page, click on Power Management to expand it and view the subsettings...