Computer will not shutdown - Starts up instantly with no button pressed

Discussion in 'Asus' started by fred, Mar 22, 2006.

  1. fred

    fred Guest


    Accidently plugged the power cord into the computer while the power cord
    was live. This made the computer boot up the instant the power cord
    touched the contacts in the power supply socket. Now the computer is
    permanently on and cannot be turned off except by turning off at the
    wall. Motherboard is an ASUS A7S8X-MX. Power supply is a 320W ATX
    switching power supply.
    Symptoms are:

    - shutting down computer from winXP makes computer go into some sort of
    "sleep mode" (the power LED flashes) and the power supply fan continues
    to spin, onboard power LEDs on motherboard remain lit.

    - the Reset button works properly. Causes computer to cold boot.

    - computer boots instantly as soon as power is given to the power cord.

    - power button does nothing. Doesn't turn off computer. Doesn't wake
    computer from "sleep mode". Doesn't turn computer off when held down for
    10 seconds or longer. It behaves as you would expect if the power button
    had not even been connected - although in actual fact it is connected.

    I have tried turning all power button/power management settings on and
    off in the BIOS. This makes no difference. I have also tried clearing
    the CMOS and removing the battery. No change.

    Obvious things like all power cords and jumpers and power switch
    internal connectors are in place/plugged in.

    What have I got? A dead ATX power supply or dead main board?

    Any help appreciated.
    fred, Mar 22, 2006
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  2. fred

    * * Chas Guest

    Yes or yes or both.

    Do you have another PS that you can try in this system? Generally what
    you did with the power cord shouldn't have had much affect on your
    system. I do it all of the time when I'm working on a PC that doesn't
    have an On/Off switch on the PS.

    Unless there was an existing problem, an ATX mobo should turn off when
    you disconnect the power cord from the PS and not turn the PC back on
    until you hit the Start button.

    Check to make sure that the Start or Reset buttons are in a stuck on
    condition. You might want to check the BIOS for Wake On settings - Wake
    on LAN, Wake on Modem and so on.

    Have you checked that the wires from the Start, Restart and other front
    panel connections are on the proper mobo pins?

    Good luck...

    * * Chas, Mar 22, 2006
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  3. fred

    GinTonix Guest

    Check this one out with a multimeter (or some creative way, like a
    battery and a suitable small light bulb). Maybe the power button
    (including the wiring) is malfunctioning and causing some funny effects?
    Me too, and one of those computers act somewhat like Fred described. I
    always supposed it was a feature, not a fault :)
    Partially right. In most newish mobos you can tune this feature in bios
    - state after power loss or something like that it is called. You can
    set it on or off. On some mobos there is a setting called "previous",
    which means the 'puter will be on when the power returns, if it was on
    when the power was lost, or it will be off when the power returns if it
    was off when the power was lost. Try changing this one to "off" to see
    what happens, this would mean the computer will be off after unplugging
    and replugging. But wait a second - carefully reconsider this one. If
    the mobo is broken in such a way that the power button does not do
    anything then you are screwed. That's what I would try, anyway. Another
    one would be writing down all the settings in bios and resetting it,
    then re-entering the data. Maybe the original "wire boot" messed it somehow?
    GinTonix, Mar 22, 2006
  4. fred

    fred Guest

    I have tested both the switch and wires to the motherboard with a
    multimeter, and all are working correctly.
    I plugged in another (known working) power supply. It made no difference.
    So that seems to confirm that it's my mobo which has had something got
    fried :(
    I think it has indeed "messed" it. All BIOS settings for making the
    computer "wake" or power on after a power cut etc. have been disabled to
    no effect. I have even enabled each of the different wake settings -
    LAN, ring, key/mouse press, password etc... and then disabled them to
    see if that worked but still no luck.

    If there is no way to fix this, short of buying a new mobo, then it
    looks like I will just have to put up with it till I get a new one.
    fred, Mar 22, 2006
  5. fred

    * * Chas Guest


    One last suggestion, unplug the HDD or HDDs and see what happens. This
    will rule out an OS problem.

    Also, when in doubt you can always go in the BIOS an hit F9 or F10 to
    reset the BIOS defaults or safe mode or what ever it's called in your

    * * Chas, Mar 22, 2006
  6. fred

    fred Guest

    I already tried booting with no HDD connected. And isn't clearing the
    CMOS and removing the battery the same thing as resetting the BIOS defaults?

    Thank you for your help.
    fred, Mar 22, 2006
  7. fred

    Rob Hemmings Guest


    Not necessarily - it's best to use the option in the BIOS to load
    the defaults after clearing the CMOS. TBH, I don't think it's
    going to help in this case, but you should try it.
    Rob Hemmings, Mar 23, 2006
  8. fred

    Anon Guest

    Turn off wake on pci event in bios or remove modem/network cards, my
    modem has this affect
    Anon, Mar 23, 2006
  9. fred

    fred Guest

    As it appears clear now that the main board is rooted, do you think it
    is going to suffer any more damage or cause damage to other
    cards/components inside if I continue to use it?
    Is using the wall switch as the 'power on/off' switch likely to cause
    further damage?

    The computer seems to run fine apart from the 'not being able to shut it
    down' problem. When I shut down Windows it just goes into the blinking
    light sleep mode and that is when I switch the power off at the wall.
    fred, Mar 27, 2006
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