You can apply several power management features in ESXi that the host hardware provides to adjust the balance between performance and power. You can control how ESXi uses these features by selecting a power management policy.

Selecting a high-performance policy provides more absolute performance, but at lower efficiency and performance per watt. Low-power policies provide less absolute performance, but at higher efficiency.

You can select a policy for the host that you manage by using the VMware Host Client. If you do not select a policy, ESXi uses Balanced by default.

Table 1. CPU Power Management Policies
Power Management Policy Description
High Performance

Do not use any power management features.

Balanced (Default)

Reduce energy consumption with minimal performance compromise

Low Power

Reduce energy consumption at the risk of lower performance


User-defined power management policy. Advanced configuration becomes available.

When a CPU runs at lower frequency, it can also run at lower voltage, which saves power. This type of power management is typically called Dynamic Voltage and Frequency Scaling (DVFS). ESXi attempts to adjust CPU frequencies so that virtual machine performance is not affected.

When a CPU is idle, ESXi can apply deep halt states, also known as C-states. The deeper the C-state, the less power the CPU uses, but it also takes longer for the CPU to start running again. When a CPU becomes idle, ESXi applies an algorithm to predict the idle state duration and chooses an appropriate C-state to enter. In power management policies that do not use deep C-states, ESXi uses only the shallowest halt state for idle CPUs, C1.

Select a CPU Power Management Policy

You set the CPU power management policy for a host using the vSphere Client.


Verify that the BIOS settings on the host system allow the operating system to control power management (for example, OS Controlled). If the host hardware does not allow the operating system to manage power, only the Not Supported policy is available. (On some systems, only the High Performance policy is available.)


  1. Browse to the host in the vSphere Client.
  2. Click Configure.
  3. Under Hardware, select Overview and click Edit Power Policy.
  4. Select a power management policy for the host and click OK.
    The policy selection is saved in the host configuration and can be used again at boot time. You can change it at any time, and it does not require a server reboot.

Configure Custom Policy Parameters for Host Power Management

When you use the Custom policy for host power management, ESXi bases its power management policy on the values of several advanced configuration parameters.


Select Custom for the power management policy, as described in Select a CPU Power Management Policy.


  1. Browse to the host in the vSphere Client.
  2. Click Configure.
  3. Under System, select Advanced System Settings.
  4. In the right pane, you can edit the power management parameters that affect the Custom policy.
    Power management parameters that affect the Custom policy have descriptions that begin with In Custom policy. All other power parameters affect all power management policies.
  5. Select the parameter and click the Edit button.
    Note: The default values of power management parameters match the Balanced policy.
    Parameter Description
    Power.UsePStates Use ACPI P-states to save power when the processor is busy.
    Power.MaxCpuLoad Use P-states to save power on a CPU only when the CPU is busy for less than the given percentage of real time.
    Power.MinFreqPct Do not use any P-states slower than the given percentage of full CPU speed.
    Power.UseStallCtr Use a deeper P-state when the processor is frequently stalled waiting for events such as cache misses.
    Power.TimerHz Controls how many times per second ESXi reevaluates which P-state each CPU should be in.
    Power.UseCStates Use deep ACPI C-states (C2 or below) when the processor is idle.
    Power.CStateMaxLatency Do not use C-states whose latency is greater than this value.
    Power.CStateResidencyCoef When a CPU becomes idle, choose the deepest C-state whose latency multiplied by this value is less than the host's prediction of how long the CPU will remain idle. Larger values make ESXi more conservative about using deep C-states, while smaller values are more aggressive.
    Power.CStatePredictionCoef A parameter in the ESXi algorithm for predicting how long a CPU that becomes idle will remain idle. Changing this value is not recommended.
    Power.PerfBias Performance Energy Bias Hint (Intel-only). Sets an MSR on Intel processors to an Intel-recommended value. Intel recommends 0 for high performance, 6 for balanced, and 15 for low power. Other values are undefined.
  6. Click OK.