Defrag Tools #168 - Powercfg Sleep Study

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In this episode of Defrag Tools, Andrew Richards and Chad Beeder talk to Nashaat Soliman and Paresh Maisuria (program manager and developer from the Windows kernel power team) about the "Sleep Study" feature in the Powercfg tool, and how you can use it to diagnose battery drain issues on Modern Standby systems.

For related content on power management and analysis using Powercfg, refer to the following earlier episodes:

For additional details on Sleep Study, see this blog post:


[00:00] Welcome and introductions
[02:55] Powercfg Sleepstudy requires a system capable of Modern Standby. What is this compared to traditional standby?
[07:03] You can specify a report duration (up to the last 28 days) and look at the resulting report file
[08:57] %Low Power State Time columns indicate how much the system was in the lowest power state during each standby session
[10:13] Click on a table row for details, including a chart of how often the system was woken up to do work
[15:38] Top Offenders list of who woke up the system
[17:15] Nashaat's system is an engineering sample which includes a special Energy Meter chip to enable more accurate power usage data (Jorge Novillo mentioned this in Episode #157 as well). Useful in debugging preproduction hardware.
[18:46] Example 1: TV capture device keeps the system from entering standby
[21:01] The list of devices we monitor, which are expected to be powered down during standby, is in a firmware table provided by the system manufacturer. We can see these in the report.
[25:44] Example 2: Standby settings configured incorrectly on the system. The Sleep Study report shows idle standby was disabled.
[29:29] Example 3: A particular desktop app which prevents us from entering standby for 5 minutes
[32:09] Pros and cons of Sleep Study vs. manual analysis via Windows Performance Toolkit

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The Discussion

  • User profile image

    I've got the opposite problem of a system not going to sleep: my desktop pc is going to sleep while I'm using it. Playing a game, watching Netflix, browsing the web and suddenly the system goes into hibernation.

    The eventlog says the cause is the battery. I do have a UPS battery connected but I'm pretty sure the system was not running from the battery. I've never had this problem with Windows 7 and 8 but since I upgraded to Windows 10 this hibernation event occurs a couple times a week.

  • User profile image

    @ZippyV: It must be hibernating in response to a message from the UPS about the battery getting too low. Not sure why that would happen if you're on AC power, maybe a faulty UPS battery?

  • User profile image

    Check your UPS - should have a  test button on the front or back and  check that the battery  is working ( take battery out of ups and check with multimeter for the battery stated voltage) if the batter meter is saying fully charged - ups batteries should be checked every 12 months for damage  and capacity  and replaced every 24 months .

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