OptiPlex 7020 (i5-14500)

Screen-Off–Triggered ACPI C-State Transition Failure and DPC Accumulation on Windows 11 25H2

(WPA Trace Observations for BIOS / ACPI Review)

Target Environment

• Dell OptiPlex 7020 SFF
• Intel Core i5-14500
• BIOS v1.23.1 (latest at the time of observation)
• Windows 11 25H2 (clean installation, no third-party software)
• Reproduced on more than 10 identical systems across multiple organizations

Purpose of This Post

This post shares observations from WPA (Windows Performance Analyzer) traces regarding a Screen Off–triggered DPC accumulation issue observed on Windows 11 25H2.

The focus is on C-State transition behavior observable from the OS side, and the purpose is to request evaluation and guidance from a BIOS / ACPI AML implementation perspective.

I am not a kernel or ACPI implementation engineer; the following content is therefore limited to observed behavior and a structured summary of trace findings, rather than a definitive diagnosis.

Observed Behavior

• Each Screen Off (display power-off) event incrementally degrades overall system responsiveness
• After sufficient accumulation, Explorer context menus stall for several seconds
• A system reboot fully restores responsiveness temporarily, indicating a cumulative effect
• The issue does not reproduce on Windows 11 24H2 under the same hardware and BIOS configuration

Key Findings from WPA Analysis

Target C-State is consistently C1E while Actual remains C1 across all CPUs

1. C-State Target vs. Actual Mismatch

• The OS consistently requests State 2 (C1E) for all logical processors
• The Actual state remains State 1 (C1) across all CPUs
• As a result, C1E transitions never appear to complete, despite repeated requests

Per-CPU Target C-State Requests (All cores request C1E)

2. Per-CPU Target Consistency

• All cores (CPU 0–7) request C1E as the target state
• No per-core deviation or selective request behavior is observed

DPC Execution Time showing ACPI.sys!ACPIDevicePowerDpc spikes

3. DPC Cost Associated with the Failed Transition

ACPI.sys!ACPIDevicePowerDpc

• Invocation count: 469
• Maximum execution time: ~90.275 ms
• Cumulative DPC time: ~3,571 ms

Even with correct symbol resolution, the call stack is empty. This suggests the execution time is not spent in a normal software call path but is consistent with a busy-wait while awaiting a hardware or firmware response.

Secondary impact observed:

• storport.sys!RaidAdapterRedirectDpcRoutine
• Invocation count: 10,914
• Cumulative time: ~3,270 ms

ACPI / BIOS-Oriented Observations (Requesting Engineering Evaluation)

• C1E is one of the most fundamental processor idle states defined by the ACPI specification. Observing system-wide failure to complete C1E transitions on all CPUs is not typical behavior from an OS-visible perspective.
• The repeated ~90 ms duration observed in ACPIDevicePowerDpc suggests the presence of a timeout or completion-wait path in the C-State transition process.
• The fact that this behavior appears only on Windows 11 25H2 raises the possibility that changes in the OS power management stack result in more explicit or frequent C1E requests, potentially exposing a previously non-fatal or latent behavior in the BIOS-side C-State handling path.

Context from Dell ProSupport

Dell ProSupport has categorized this as a “platform issue.” Given that C-State handling logic and ACPI AML behavior are implemented in BIOS firmware, these findings are shared to request BIOS-level technical review and interpretation.

Request for Guidance

• How this observed behavior appears from an ACPI / AML implementation standpoint
• Whether the C1E transition behavior requested by Windows 11 25H2 aligns with platform expectations
• Whether this type of behavior could reasonably be addressed or mitigated via a BIOS update

Data Availability

Due to organizational policy, the original .etl trace file cannot be shared. However, additional WPA screenshots or specific extracted views can be provided if they would assist further analysis.