Windows Guest OS reports incorrect CPU clock speed after vMotion

Products

• VMware vSphere ESXi
• VMware vCenter Server 8.0

Issue/Introduction

After performing a vMotion migration of a Windows virtual machine from a source host to a destination host with a different CPU clock speed, the Windows Guest OS continues to report the CPU clock speed of the original source host.

Symptom: Task Manager and System Properties (sysdm.cpl) display the old CPU frequency.
Scope: This issue affects Windows Virtual Machines migrating between hosts with dissimilar processor speeds, even if Enhanced vMotion Compatibility (EVC) is enabled.

Environment

vCenter/ESXi 8.x
Windows (All versions)

Cause

This issue occurs because the Windows operating system determines the CPU characteristics (including clock speed) during the boot sequence (initialization). This information is cached by the OS for display purposes.

During a vMotion operation, the virtual machine's memory and execution state are transferred instantly without a reboot. Consequently, the Guest OS does not re-initialize its hardware detection or re-query the ACPI tables to update the displayed clock speed, resulting in stale reporting.

Resolution

This behavior is **cosmetic only** and does not impact the performance or actual execution speed of the virtual machine.

The virtual machine is utilizing the CPU resources of the destination host at the destination host's native clock speed.

To update the reported clock speed in the Guest OS:
1.  Restart the Windows virtual machine.