Why is my sleeping PC belching hot air?

Q. After being put into sleep mode for several hours, my Win10 Pro laptop will randomly run its fan at high speed and discharge hot air.

When I try to take it out of sleep mode and sign in, I get only a blank screen. Pressing the power button, escape key, function keys, and so forth [doesn’t wake it]. I have to hold down the power key for a forced shutdown.

There’s nothing on the screen indicating that something is running. I never had this issue with Win7 Pro. I have to believe that Win10 is running some sort of hidden processes or services while it’s ‘asleep.’ It might be actually doing Microsoft’s bidding, collecting things.  

I’ve performed malware and virus scans, and all drivers and software are up to date. Any ideas on what’s going on?

​A. It sounds like the Windows Automatic Maintenance (WAM) system is at work. Working in conjunction with Task Scheduler, WAM can wake a sleeping PC to perform whatever maintenance tasks are in the queue.

These tasks can include: running Windows Update; defragging/optimizing hard drives; doing security scans; checking for solutions to earlier Windows errors; and so on. (See the MSDN article, “Automatic Maintenance,” for Windows 10 and for Windows 8. Windows 10 builds on the Windows 8 system, and earlier Windows versions had simpler forms of Windows Automatic Maintenance. But the general concepts are the same.)

These automatic tasks, especially when running in combination, can be so CPU- and/or disk-intensive that they make the PC temporarily slow to respond to user input. That’s one reason that these heavy-duty maintenance tasks are usually scheduled during sleep mode — times when maintenance won’t interfere with normal user operations.

To learn what’s going on with your system, explore Task Scheduler to see — and possibly alter, if you wish — whatever automatic maintenance is scheduled. Also check Windows’ Reliability Monitor logs for errors at the times of the seeming-hangs.

(Originally published on Windows Secrets on Tuesday, February 23, 2016.)

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