Outlook Classic + Exchange + HP + Modern Standby (S0) = Fan Noise While Typiping Email

[Guht187]

Introduction:

In our company, we’ve identified an ongoing and fully reproducible issue that affects recent HP EliteBook generations running Modern Standby (S0), particularly when using Microsoft Outlook Classic with an Exchange account.

The issue causes the laptop fan to spin up audibly and immediately while composing even the simplest emails — including plain text — despite no notable CPU usage or system load.

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Affected hardware/software environment:

• HP EliteBook 840 G9 / G10

• HP EliteBook 1040 G9

• Windows 11 Pro (fully updated)

• Microsoft 365 Apps (Outlook Classic – desktop version)

• Exchange Online (Microsoft 365 tenant)

• Modern Standby (S0 Low Power Idle) enabled by default

• No support for S3 (not available in BIOS)

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Observed behavior:

• Fan ramps up as soon as you begin typing an email

• Occurs even when writing plain text with no formatting or attachments

• CPU usage remains low (3–5%, monitored via Task Manager)

• Happens only with Outlook Classic, not with New Outlook or Outlook Web

• Behavior is 100% reproducible across users, power plans, and environments

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Steps already taken for testing and analysis:

1. Power profile reset and optimization

• Ran powercfg -restoredefaultschemes to restore defaults

• Activated “Balanced” and “High Performance” manually using powercfg -setactive

• Created custom .pow profiles (e.g., "Outlook_Ruhig")

• Fan behavior remains unchanged

2. Modern Standby (S0) / S3 energy mode verification

• Verified via powercfg /a: S0 active, S3 unavailable

• CsEnabled registry key no longer exists (as of Windows 10 2004)

• BIOS: no option to switch between S0 and S3

• No fine-grained fan control in BIOS (e.g., "Silent Mode" not available)

3. Full Outlook reset and cleanup

• Deleted Outlook profile manually

• Removed local and server-side signatures

• Cleaned registry entries related to Outlook and Office

• Disabled AutoCorrect, proofing tools, and autocomplete

• Disabled all COM and native add-ins

• Tested in plain text mode

4. Outlook version comparison

• New Outlook: significantly quieter, but missing enterprise features (e.g., COM Add-ins, full calendar support)

• Outlook Web: quieter, but insufficient for enterprise workflows (e.g., no offline capability, limited integration)

5. System-level monitoring and analysis

• OUTLOOK.EXE observed using 3–5% CPU during email typing

• Fan still responds aggressively

• Verified using Task Manager and Resource Monitor — no additional background load

6. Support engagement and feedback

• Contacted Microsoft Support (multiple sessions + escalation)

• Microsoft acknowledged issue but stated it's tied to firmware and OEM design (HP, Surface, ThinkPad)

• Ticket still open, no product-level workaround or roadmap confirmed

• Feedback submitted via Microsoft Feedback Hub

• Published detailed report in Microsoft Community

• Preparing HP community post and internal documentation for potential escalation

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Likely root cause:

• Outlook Classic uses WordEditor.exe, even for plain text emails

• Exchange automatically saves to Drafts every few seconds

• These small background actions cause minor but constant CPU load

• Modern Standby (S0) reacts to any system activity, keeping the system “awake”

• HP firmware likely prioritizes responsiveness, causing immediate fan activation

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Our assessment:

This is not a random glitch — it’s a design-level interaction between:

• Microsoft Outlook Classic

• Exchange Online

• Modern Standby (S0)

• HP device firmware and thermal profiles

The inability to switch to S3 or customize fan response makes the situation worse.

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What we hope to see from HP:

1. Official acknowledgment of the issue

2. BIOS-level option to enable S3 if technically possible

3. Better fan control settings in BIOS for S0 behavior

4. Cooperation with Microsoft to resolve the problem at the integration level

5. (Optional) Firmware update optimized for modern office usage scenarios

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We hope that by sharing this, other affected users can contribute their experiences — and that HP can take this feedback seriously in the interest of power-efficient, quiet, professional computing.

Thank you,
Guht187