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26 Nov 2011  

Windows 7 Home Premium 64 Bit
Shut down computer, remove all power sources, hold down power button

Why does shutting down the computer, removing the AC Adapter, removing the battery (if it is a laptop), and holding down the power button for 30 seconds fix problems in one's computer. I was recently corrected in a post of mine that this does not actually do anything unless one removes the 3 volt battery from the motherboard, but I know this is not true from experience. Here is the correction I am referring to from a more experienced member:

Quote   Quote: Originally Posted by TVeblen View Post
I'm sorry, but I feel I need to correct misinformation. Lots of folks read these posts.

The motherboard has a 3 volt battery installed in it. This battery provides just enough power to retain all of the BIOS settings regardless of the state of the main power or the power supply. Following the steps above will not reset the BIOS or the CMOS chip.

You can reset the BIOS defaults by selecting that option from within the BIOS settings. Usually on the Exit menu.

To reset the CMOS (Clear the CMOS chip) there will be either a jumper on the motherboard to perform this function with, or newer boards have an actual reset button.

The above procedure will work to restore the BIOS defaults if you add the step:
2b - remove the 3v battery.
But it will not clear the CMOS.
The reason I know that doing the hardware reset I described initially works:

1. I have a laptop that occasionally suffers from a USB Device Error issue. Every port gives me the message that the USB Device Is Not Recognized. If I follow the steps initially outlined in this post, it fixes my issue. I have done this at least 10 times.
2. My roommate a few years ago was unable to load Windows from his brand new laptop after just six months of owning the machine. The screen would not even show the BIOS options. We tried a half dozen times to get it to load by turning it off and back on. Finally, I turned it off, unplugged the AC adapter then unplugged the battery, and held down the power button for 30 seconds. Plugged the battery back in, plugged the AC adapter back in, and presto, Windows ran like nothing had ever been wrong.
3. I have been doing troubleshooting with my girlfriend's laptop and her family's computers (four laptops and a desktop) and have fixed all four laptops from various boot issues and crash issues using the method that apparently does not perform any sort of reset.

I have asked computer people why the method works; I have asked electrical engineers why the method works. The only answer that makes sense to me is an electrical engineer told me that holding down the power button with no power going into the machine allows the capacitors to drain by closing the circuit. I have yet to get an entirely satisfactory answer other than it performs some sort of hardware/BIOS/CMOS reset, which apparently is incorrect.

So is it magic? Or does someone out there actually know what it does?
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