Sunday, October 18, 2015

PC Hardware: Why does my PC wake up?

Windows PCs may wake up on their own for a variety of reasons ranging from network adapter settings to Windows configuration. The list is in no order of precedence and covers Windows but could be applicable to Linux and OS X. The configuration details will vary by OS. These may apply to waking from sleep, hibernation, or power off.
  • Network (NIC) adapter settings
    NICs include settings to wake the operating system. These include:
    • Wake on Magic Packet
    • Wake on Pattern Match
    • Wake on Magic Packet from power off state
    • Wake on Link Settings

    These settings are applicable more to an enterprise environment rather than home or small business use. To disable:
    1. Right click My Computer, Computer, or This Computer based on the version of Windows.
    2. On the left select Device Manager in the Computer Management list.
    3. Expand Network adapters in the device tree.
    4. Right click a network adapter and select Properties.
    5. Select the Power Management tab.
    6. Uncheck any of the options dealing with waking the computer.
      Example Intel NIC properties
    7. Click OK to save the settings.
    8. Repeat for any remaining NICs.
  • BIOS/UEFI Settings
    Wake timers in the motherboard/system BIOS or UEFI may cause the system to wake.
    1. Enter the BIOS or UEFI using the appropriate keyboard entry. Check with your PC or motherboard documentation for the exact procedure. Usually pressing the Delete or F2 keys over an over during boot will allow access.
    2. Look for any settings dealing with wake timers or wake parameters. Check with your PC or motherboard documentation for any precautions.
    3. Save the settings and reboot the PC.
  • Scheduled tasks
    Some scheduled tasks may wake the computer. The task can be configured to not wake the PC.
    1. Search for Task Scheduler in the start menu or task bar search and click it to start. You must have administrator privileges.
    2. Examine the Conditions tab to see if Wake the computer to run this task is checked. Be cautious as some of the tasks are vital for system health. To disable the wake feature, click on the Properties option. Be sure to save the changes by clicking the OK button.
    3. Close Task Scheduler when finished.
Windows Task Scheduler
[Update: 10/19/2015]
  • Allow wake timersPower options allow the system to wake up due to timers. To disable:
    1. In the start menu or desktop search, type in Power Options and launch it by clicking.
    2. Click Change plan settings next to the plan current in effect (selected).
    3. Click Change advanced power settings.
    4. Expand the Sleep section of the tree and then Allow wake timers.
    5. Click the Enable link next to Setting to change. Note that Windows maintenance processes may or may not wake the computer if this setting is disabled.
    6. Click the OK button to save and then exit Power Options.
[End Update]

One last item is background applications. Anti-virus, anti-malware, maintenance, and other applications including OS tasks may wake the computer from sleep or hibernation and occasionally from power off. To determine if a background application is causing the issue, examine the settings for each of the third party applications and any Windows settings that may be at fault.

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