Technical Inquiry: 90ms ACPI DPC Spike on Raptor Lake S (Win11 25H2)

[e13mako]

Hello,

I am an IT administrator seeking technical insight regarding a specific performance observation on the Raptor Lake S platform (specifically i5-14500 / OptiPlex 7020) under Windows 11 25H2.

The Observation:
Using Windows Performance Analyzer (WPA), we have identified a recurring ~90ms DPC spike in ACPI.sys!ACPIDevicePowerDpc triggered during screen-off events. This behavior has been verified across multiple identical systems in a clean OS environment.

Key Findings:

• C-State Transition: WPA traces indicate that during these spikes, the CPU Idle State Target is State 2 (C1E), but the Actual State remains stuck at State 1.
• Execution Pattern: Despite full symbol resolution, the call stack for the duration of the 90ms spike remains empty, which suggests a hardware-level polling or spin-wait loop within the firmware/ACPI layer.
• AML Analysis: A preliminary review of the ACPI Machine Language (AML) tables suggests the existence of a specific wait-state or polling routine that appears to correlate with the observed 90ms duration.
• OS Specificity: This symptom is currently unique to Windows 11 25H2 and is not observed on 24H2 with identical hardware and BIOS configurations.

Inquiry:
I have attached the Intel SSU log for detailed system specifications. I would appreciate any insight on the following:

1. Are there known timing sensitivities in the Raptor Lake S C-state entry/exit sequence that could be exposed by changes in the Windows 11 25H2 power management stack?
2. Is this polling behavior during C1E transitions an expected platform characteristic, or could it be addressed via future microcode or ME firmware updates?

Supporting Data:
I have prepared detailed WPA screenshots (showing the Idle State Target vs. Actual State) and trace data. I am happy to provide these files upon request to assist with further investigation.

Best regards,

[Nikhil_Intel]

Hello e13mako,

Thank you for posting your query on the Intel Community Forum!

I see that another support request has been created for the same issue. To avoid duplicate tracking and confusion, please note that two support threads were opened for the same concern.

To keep communication clear and ensure consistent troubleshooting, this thread will now be closed and will no longer be monitored. All further updates and responses will be provided only in the other active thread.

I appreciate your understanding and cooperation. Please continue the discussion in the remaining support thread for next steps and updates.

Best regards,

Nikhil

Intel Customer Support Technician