PowerEdge LITEON PSU: System CPU Throttling Due to Power Management Alerts in Cold Redundancy Mode

Summary: Central Processing Unit (CPU) throttles to base frequency ~600 MHz in Cold Redundancy, temperature is normal; a LiteON Power Supply Unit (PSU) firmware issues an OCW‑related SMB alert, triggering a policy limiting CPU power. ...

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Symptoms

System experiences slow performance because the processors enter a throttled state.

  • CPU frequency drops to the base frequency (≈ 600 Mhz).
  • System performance degrades while in Cold Redundancy mode.
  • Thermal sensors report normal temperatures; no overheating detected.

The issue does not occur when Cold Redundancy is disabled.

Cause

A LiteON PSU firmware may incorrectly assert an OCW-related SMB Alert while the system is operating in Cold Redundancy mode. This alert triggers Power Manager Policy , which applies CPU power‑limiting constraints.

Resolution

Update the PSU firmware to the version listed in the table resolves the issue. 

Prerequisites

  • Identify the affected PSU model (DPN) from the system inventory table below.
  • Go to the corresponding firmware package from Dell Support.
  • Download the appropriate firmware based on the table below and initiate the update, referring the "Installation instructions"
  • Schedule a maintenance window; ensure the system remains powered on during the update.

Update Steps

  1. Log in to the iDRAC.
  2. Go to firmware update section.
  3. Allow the update to complete; Post update reboot the system.
  4. Verify that the PSU firmware revision matches the version listed.
  5. Confirm that CPU frequency returns to normal operation and performance degradation is resolved.

    Power Supply Firmware Table:

    DPN

    Description

    FW Fix

    Y16MV

    1500W/277V

    SWB: F4W7J, FW revision: 0606

    763VM

    800WT

    SWB: HJMX9 FW revision: 1109

    1PKMH

    1500WT

    SWB: YY0YT FW revision: 1811

    D5NDX

    1100WT

    SWB: 2R7RM FW revision: 1310

    Ensure the system remains Powered On during the update.

    Affected Products

    Dell XC Core XC670, Dell XC Core XC770, PowerEdge R470, PowerEdge R570, PowerEdge R670

    Products

    PowerEdge R770, PowerEdge R770AP
    Article Properties
    Article Number: 000486739
    Article Type: Solution
    Last Modified: 14 أغسطس 2026
    Version:  1
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