Great question — this is the right thing to ask, because “idle” in Windows does not mean just “I’m not touching the keyboard”.

Below is the exact, documented definition Windows uses, and how it applies to the Scheduled Task you created.

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✅ How Windows defines Idle (official definition)

For Task Scheduler (including On idle triggers), Windows considers the system idle only when BOTH conditions are true:

1️⃣ User absence

• No keyboard or mouse input
• On modern Windows (8/10/11):
  • User is considered absent after ~4 minutes of no input

2️⃣ Low system activity

• CPU AND disk activity must be mostly idle
• Threshold:
  • CPU + disk must be idle for ~80–90% of the check interval
• Low‑priority background threads do not count as activity

✅ This definition is straight from Microsoft’s Task Scheduler documentation [learn.microsoft.com]

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🧠 What counts as activity (prevents idle)

Even if you don’t touch the keyboard, the system is NOT idle if:

• CPU usage is sustained
• Disk I/O is active
• Backup software is running
• Antivirus scan is active
• Indexing is running
• A VM is active
• A service is doing regular work

✅ Any of these resets or blocks the idle state [learn.microsoft.com]

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🎥 Media playback exception (important)

If an application sets:

ES_DISPLAY_REQUIRED

(for example, video players or browsers playing video)

Then Windows explicitly refuses to consider the system idle, even with:

• No keyboard input
• Low CPU usage

This is intentional so:

• Videos don’t stop
• Presentations don’t sleep

✅ Documented by Microsoft [learn.microsoft.com]

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⏱️ How often Windows checks for idle

Windows does not check continuously.

• When user is present → checks roughly every 10 minutes
• When user is absent → checks every ~30 seconds
• Certain events force a recheck:
  • Power source change
  • Battery level change
  • User presence change

✅ Documented behaviour [learn.microsoft.com]

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✅ How this applies to your auto‑hibernate task

Your Scheduled Task triggers when:

✅ No keyboard/mouse input
✅ CPU + disk mostly idle
✅ For X continuous minutes (the idle duration you set)

Then it runs:

shutdown /h

If any of the following happens:

• Background CPU spike
• Disk activity
• Media playback
• Mouse movement
• Keyboard input

➡️ Idle timer resets

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❌ What idle does not mean

Assumption	Reality
“Idle = no user input”	❌ Also needs low CPU + disk
“Idle is exact to the minute”	❌ Checked in intervals
“Idle respects power timeouts”	❌ Separate system
“Idle works like screen timeout”	❌ Different subsystem

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✅ Why this is still better than Windows hibernate timeout

Even with these rules:

• ✅ Task Scheduler idle actually works on S0 systems
• ❌ Power Options hibernate timeout does not
• ✅ shutdown /h always forces S4
• ✅ This is the most reliable automation available

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✅ If you want keyboard/mouse only idle (advanced)

Windows cannot do this natively.

Task Scheduler always includes CPU/disk checks — this is by design [superuser.com]

Workarounds:

• Custom PowerShell script using GetLastInputInfo
• Third‑party idle detectors
• Adding a delay inside the task itself

(Only needed in edge cases.)

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🧠 Short, practical summary

Windows considers your PC idle when:

• You haven’t touched keyboard/mouse ✅
• CPU + disk are mostly quiet ✅
• No active media/presentation ✅
• For the entire idle duration ✅

If any of those break → idle resets.

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Hi,

Sorry, Dell never did resolve the non-sleep issue. Got returned the 2250 to Dell in November for a full refund.

Maybe Dell shipped you the one I returned??

Mike

Calgary