Posts: 8
Member Since: ‎07-27-2009
Message 1 of 2 (1,449 Views)
Accepted Solution

Spontaneous power on after Vista upgrade

I have a dv2000t notebook PC (EQ883AV) that I bought in 2006.  It has a "Vista Capable" sticker on it.


I won't bore everyone with details as to why, but my situation required a fresh install of Vista Home Premium.


Everything went fine except that when my notebook is hibernated it will spontaneously power on after several hours.


I've scoured the forums here and Googled around but haven't found anyone else who's had this problem.


Has anyone ever heard of this?






Posts: 8
Member Since: ‎07-27-2009
Message 2 of 2 (1,440 Views)

Re: Spontaneous power on after Vista upgrade

A bit more Google-ing and I found an answer to this perplexing problem.


First, a bit more detail on my specific problem and some related problem reports I came across out there in the ether.


When I'm done using my computer I press the power button which is configured to put my computer into hibernation.


Some mornings I would come downstairs to find my computer powered on with the BIOS Power-On Password "Enter Password" prompt displayed.  Other mornings my computer would not power on because the battery was drained.


Others reported their computers waking up from sleep or hibernation at various times, some repeatedly, and then going back to sleep.


So what's going on?  It's all related to timers.


A program can tell Vista wait a certain period of time and then invoke some executable code at an address the program provides.  An example is if you use a program like Microsoft's Outlook email client where you can set a reminder task for a future date and time.  Outlook tells Vista to wait X amount of time and then execute some Outlook code.  That Outlook code then displays your reminder.


But what happens if you put your computer to sleep or into hibernation?  Well, before Vista you wouldn't get your reminder.  Or maybe your anti-virus scan wouldn't happen.  Or maybe Windows Update wouldn't run.  Vista changed all that.


When Vista goes to sleep or into hibernation it first checks to see if there are any timers set to go off.  If there is, it takes the next timer set to go off and sets an alarm in the platform hardware for that day and time.  In the hardware this is typically an alarm that's part of the real time clock (RTC).  Once Vista sets the RTC alarm it goes to sleep or into hibernation.


When the RTC alarm goes off your system turns on.  Vista resumes and is notified of the alarm having gone off.  Vista checks its timer list and executes the code associated with the timer that when off.  When the code is done executing Vista will go back to sleep after two minutes of idle time.


My problem was compounded by the fact that I was using the BIOS Power-On Password.  My computer would sit at the "Enter Password" prompt until I happend upon it or the battery ran down.


What's the fix?  It's pretty simple.  Click Start, All Programs, Accessories, Command Prompt.  Execute these two commands in the Command Prompt window:


powercfg -setacvalueindex scheme_current sub_sleep bd3b718a-0680-4d9d-8ab2-e1d2b4ac806d 0

powercfg -setdcvalueindex scheme_current sub_sleep bd3b718a-0680-4d9d-8ab2-e1d2b4ac806d 0


What do these commands do?  You're modifying the setting of the "Allow windows to automatically wake your computer from sleep on a timer for scheduled tasks and other programs" attribute (that is honestly what it's called!) in the Sleep settings subgroup of your current Windows power plan.  The first command applies when you're running on AC power and the second when you're running on DC (battery) power.  You can re-enable either attribute at any time by re-executing the command changing the 0 at the end to a 1 (0 = turn it off, 1 = turn it on).


WARNING: If you turn these settings off, then your computer will NEVER wake-up from sleep or hibernation to perform scheduled tasks.


You can read and learn more about power profiles here:


and here:


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