# Modern Standby: is the laptop actually sleeping?

> How S0ix differs from S3, why a closed laptop drains battery, and how to find out what kept the machine awake.

**Tested on**

- Build: 26300.9457
- Edition: Pro (26H2)
- Architecture: x64
- Evidence: E1
- Verified: 2026-10-29

## The short answer

Most modern laptops do not **sleep** in the old sense. They use **Modern Standby (S0 low-power idle)**: the system stays in a low-power state with the OS still running, so it can wake instantly and keep network tasks alive.

The trade-off is real:

- wake is fast (no hibernate resume);
- background work can continue — including work you did not want;
- a misbehaving driver or app keeps the SoC out of its deepest idle state, and the laptop drains in a bag.

S3 (the old suspend-to-RAM) is rare on new machines; the firmware decides which model is available, not Windows.

## Check which model the machine uses

```powershell
# which sleep states are available
powercfg /a
# what the platform actually supports (S0ix low-power idle)
powercfg /sleepstudy /output $env:TEMP\sleepstudy.html
```

`powercfg /a` prints something like:

- `待机 (S0 低电量待机)` — Modern Standby is active;
- `待机 (S3)` — classic suspend;
- `休眠` — hibernate available or not.

If S3 is not listed, you cannot switch to it with a setting. Some OEM firmwares expose a "S3 sleep" option in BIOS; most new machines do not.

## Verify the drain with data, not impressions

```powershell
# battery report: capacity and recent drain
powercfg /batteryreport /output $env:TEMP\battery.html
# what woke / kept the system awake
powercfg /sleepstudy /output $env:TEMP\sleepstudy.html
```

The sleep study shows sessions by duration and **the top offenders** that prevented deep sleep: a driver, a service, or a scheduled task. Open the HTML in a browser; the tables are readable.

Typical offenders:

| Culprit | Tell |
|---|---|
| Network adapter (WoWLAN) | network activity during standby |
| USB device / dock | device remains powered |
| Indexing or backup task | scheduled task ran during standby |
| Browser with audio/video | process held a power request |
| Driver bug (GPU/audio) | no obvious app, but active time high |

## Find the process holding a power request

```powershell
# requires the appropriate privilege; shows requests preventing sleep
powercfg /requests
```

This is the fastest single command for "the lid is closed, why is it warm". It lists **display**, **system** and **away mode** requests with the requesting process. Close that process and retest.

## Reduce the drain without disabling standby

1. **Disable wake-on-LAN / WoWLAN** if you do not need it.
2. **Unplug the dock** when the laptop travels — docks keep devices powered.
3. **Check scheduled tasks**: `Get-ScheduledTask | Where-Object { $_.Settings.WakeToRun }`.
4. **Update the GPU/audio drivers** — these are the most common standby regressions.
5. **Hibernate after a timeout** if standby drain is unacceptable; hibernate is slower to resume but loses nothing.

> **Caution: Do not leave a laptop in a bag at 100% on Modern Standby**
>
> A machine that wakes in a bag runs hot with no airflow. If standby drain is unavoidable, shut down or hibernate before packing. Repeated hot-bag cycles are hard on the battery.

## What "connected standby" does to battery over a day

Rough expectations from vendor data (not a measurement here):

- a healthy machine loses low single-digit percent overnight;
- losing more than ~5%/hour in a bag means something is holding the system awake;
- a machine that is warm to the touch after 30 minutes in a bag is not idle.

Use the sleep study's per-session active/residency numbers rather than a single percentage.

## Related

- [Battery report](https://windows.homes/en/hardware/laptop/battery-report/)
- [Throttling: thermal or power](https://windows.homes/en/hardware/laptop/throttling/)
- [Power plans](https://windows.homes/en/hardware/laptop/power-plans/)

## Lab boundary

E1. S0ix/S3 behaviour is documented by Microsoft and implemented by firmware. The lab's virtual machines have no battery and no S0ix path, so no drain was measured here.

## Sources

- [Microsoft Learn — Modern Standby](https://learn.microsoft.com/en-us/windows-hardware/design/device-experiences/modern-standby)
- [Microsoft Learn — System power states](https://learn.microsoft.com/en-us/windows/win32/power/system-power-states)
- [Microsoft Learn — Powercfg command-line options](https://learn.microsoft.com/en-us/windows-hardware/design/device-experiences/powercfg-command-line-options)

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Source: https://windows.homes/en/hardware/laptop/modern-standby/