Windows 8 Default Shutdown is not a complete shutdown to S5 State - causes Power On by RTC to fail.

This is not a question but an advisory to users of Windows 8 who also wish to use BIOS function of Power On by RTC.  Power On by RTC allows a computer to automatically start from Shutdown S5 Power State at a specified time.


Windows 8 Power Plan options specify by default 'Fast Startup'.  Fast Startup documentation specifies that Windows maintains system information in a file at Shutdown and then when computer is restarted it will restore the system from this file of information making startup faster.  Restarts are not affected by Fast Startup.


If you know what Hybrid Sleep is this is very similar to what Hybrid Sleep is.  And in fact that is very much what is happening because when you attempt a Shutdown with the Fast Startup option in effect, the computer goes into an S4 power state which is not a complete Shutdown to the S5 power state or in other words down to Standby Power.


The default for Windows prior to Windows 8, at least for Desktops, was to do a complete Shutdown to the S5 Power State. In order for Power On by RTC to work, the computer apparently needs to be in the S5 Power State or a complete shutdown.  People who were using Power On by RTC when upgrading to Windows 8 will find that the Power On by RTC will stop working and without any obvious explanation since the Fast Startup Power Option never existed before.  I spent at least a week to 2 weeks before I discovered what the problem was.  And at first when I found the Fast Startup Power Option, I didn't believe that was the problem but did not forget about it and finally after watching my Motherboard's Q-Codes (Status Codes), I saw that the Computer was doing a shutdown to the S4 State which confirmed to me that the Fast Startup had to be the cause.  I unselected the option and Power On By RTC started working.  To make matters worse, somehow the Blinking Case Power Light did not blink as it was supposed to when in a sleep state which also makes it difficult to diagnose this problem.


The Fast Startup Option is an option that was not necessary to put in Windows 8 as the same function could be achieved optionally before in the prior versions of Windows and by placing this option as default it causes a lot of headaches for those of us who use Power On By RTC.  I am not the only person who has had this problem because I have seen posts in other forums where this has occurred as well.  As far as I could tell from my researches I am the only one who discovered the cause of this problem, at least in the forums.


3-2-13 Correction to above statement.  The S4 State is not Sleep but rather Hibernate.  All of the above statements otherwise are correct as far as I know and the cause of Power On By RTC is definitely correct with the solution stated also being the correct solution.


Question Info

Last updated March 24, 2018 Views 842 Applies to: