Solved PC not waking up with task scheduler

[btb12]

Can anyone help troubleshoot why the pc isn't waking when a task is scheduled to wake it? It sleeps, S3, I can wake with the power button, and can WOL, but a task set to wake it is not working. Allow wake timers is enabled in power configuration, and BIOS settings are correct as it woke up when had Win7 installed.

I've set a task manually, and used an alarm program that wakes it, but neither work, what can I check to resolve this?

Thanks for any help.

 

[MilesAhead]

You could try this as a guide:
http://www.eightforums.com/tutorials/14264-windows-defender-scheduled-scan-set-up-windows-8-a.html

or run the tutorial as is to test if a scheduled task will wake your system as documented.

 

[btb12]

Found the reason was due to no HPET present on my system. Seems that since 8.1 HPET is a requirement for waking with task scheduler and the BIOS I was using didn't support it, there was no 'High Precision Event Timer' present under system devices. A BIOS update solved the problem and waking is OK now.

It may be that 8.1 will always require HPET, or a bug that will be fixed at some time, but for now without it the system won't wake on a schedule.

 

[MilesAhead]

Thanks for posting the solution.

 

[CharlieW]

Folks: I have a WinBook tablet (as opposed to PC) with a similar problem. A scheduled task will not wake the device. The tablet does NOT support Sleep States S1 thru S3. Instead, it supports "Connected Standby." Scheduled Tasks won't wake it from CS, but they do fire immediately after I manually wake the device after the scheduled trigger time. The device DOES have an HPET. So that's not the issue. Since it doesn't support Sleep (as we know it) the Power Options dialog doesn't even have a Sleep line-item from which to enable wake timers. I've tried to use the registry mods provided here (http://www.eightforums.com/tutorials/50074-power-options-add-remove-allow-wake-timers.html) but that has no impact. Can anyone suggest any additional path forward?