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Thread: Strange power on/off behavior on some systems

  1. #1

    Default Strange power on/off behavior on some systems

    Why do some systems, such as from Dell or Gateway, etc turn on for 1 second after you plug in the power cable and then shut off? I've seen many 90's and 2000's systems do this, so it shouldn't be a PSU issue. I don't think it's healthy for the hard drives, cause they spin up, and then quickly spin down during this occurrence. Do the OEMs want your PC to die early or something?!...

    I've had some modern systems do this after exiting the BIOS. The PC shuts down itself, then quickly turns itself back on 1 second later. On my AMD FX 9590 PC, when I was testing out Windows XP on it just for fun, it would do the funny thing after I did "restart" from the power down menu. Clicking "turn off PC" would turn it off just how a normal PC should, and then after that it stayed off. When I installed Windows 7 on this same PC, it didn't have this "restarting pc" issue. What's up with all this?

  2. #2
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    Likely there's an additional layer to the Power Management system that needs to come online first before realizing it should be in an OFF state.

    Do the OEMs want your PC to die early or something?!...
    How often does the average person unplug their PC?
    = Excellent space heater

  3. #3
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    Quote Originally Posted by NeXT View Post
    Likely there's an additional layer to the Power Management system that needs to come online first before realizing it should be in an OFF state.

    How often does the average person unplug their PC?
    Every time I turn it off. Via power strip, or switched outlet.

  4. #4

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    Quote Originally Posted by NeXT View Post
    Likely there's an additional layer to the Power Management system that needs to come online first before realizing it should be in an OFF state.

    How often does the average person unplug their PC?
    I wonder if a certain BIOS setting will prevent this power on/off behavior?

    I plug/unplug different systems often, when I want to use a different PC, and especially when I'm diagnosing problems and testing if it's working right with different components. But usually the system stays plugged in for a while if theres no problem with it.

  5. #5

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    Some features like wake-on-lan require power all the time. I've noticed some newer Dell's that will will briefly spin the fan when plugging the AC in, probably so the machine can figure out if it's supposed to be on or off when power is re-applied.

  6. #6

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    Quote Originally Posted by computerdude92 View Post
    I don't think it's healthy for the hard drives, cause they spin up, and then quickly spin down during this occurrence. Do the OEMs want your PC to die early or something?!...
    I would not condemn OEMs based on an assumption. My Dell does this and I have no doubt that it is due to the relatively-slow rise time of the efficient pilot voltage supply section for the on/off and standby circuits after power is applied. When the on/off signal is low it enables the main PS rails in the half second before the pilot supply reaches a stable 5V or whatever it is. Perhaps they could have designed it out but it seems they didn't think it was an issue.

  7. #7

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    Quote Originally Posted by paul View Post
    I would not condemn OEMs based on an assumption. My Dell does this and I have no doubt that it is due to the relatively-slow rise time of the efficient pilot voltage supply section for the on/off and standby circuits after power is applied. When the on/off signal is low it enables the main PS rails in the half second before the pilot supply reaches a stable 5V or whatever it is. Perhaps they could have designed it out but it seems they didn't think it was an issue.
    Although i'm curious, I never noticed any problems evolve from it.

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