Power Button Does Not Turn Machine Off? Turns on Though

My power button in my PC case turns on the computer, but doesn't turn it off "normally". If Windows (or whatever OS I am using) isn't locked up, I can hold it in and the OS will go through its own shutdown process. If the computer is just starting up I can hold it in a for a second or two and it turns off. However, if something happens and my OS locks up (graphics driver not loaded in Ubuntu for example) holding the button in for 5+ seconds won't do a hard shutdown.
I have ACPI 2.0 turned on in the BIOS but I'm not sure if I installed XP when it was on, and I'm not sure that has anything to do with it anyway.

I've always been under the impression if you held that power button down for a few seconds it bypassed what the OS did with it and did a hard shutdown. If my PC has been locking up I've had to just turn off the power supply.

I've had my CPU, PSU, etc. for about 3-4 years now and I've tested a lot of components. My graphics card doesn't overheat, processor doesn't overheat (and it is stable for hours overclocked when doing stress tests, core voltage isn't that much higher than stock), memtest+ 86 said there were no errors with my RAM, my internal hard drive with XP got passed on the Long DST test that Seatools does. I haven't noticed ANY blue screens or anything that is the GNU/Linux equivalent. Most of my lockups in XP happen when I am in a game, so I think my graphics card isn't working completely right (or maybe my XP install is just old and degraded and needs reinstalling), but like I said, even a lockup in a brand new Linux install can't be turned off by holding in the momentary power switch.

I have an Asus p5b deluxe wi-fi AP edition. It has been working fine since I got it. I have BIOS 1238 and I can't see any options to turn on or off the behavior of holding down the momentary power button for a few seconds.

I would think my switch is messed up, but it can turn the machine on, and it can send the signal for the OS to shutdown the machine. However, it just won't do a "hard" shutdown by holding it in for 5+ seconds at a time.

Does anyone have an idea what to do here? The only thing I haven't tested is my PSU and motherboard, and I don't have the equipment to test the former and don't know how you'd test the latter. I'm getting a new graphics card and PSU in a few days anyway, but I don't know if that has anything to do with it.

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  1. The only thing I can think is that the BIOS routes the power-off signal to the OS via an interrupt, just like you mentioned.

    Check out this. Towards the bottom of the page it talks about how XP is configured to perform an OS shutdown when the power button is pressed.
  2. A lock-up is sometimes a different matter, it that case you can also use the 'Reset Button' instead.

    I never use the power button unless I need to force shutdown and then I use the reset button is that fails.

    This article has some good information, it's focus is sleep, however the ACPI operations, Crash Analysis tool and trouble shooting are good starting points - http://support.microsoft.com/kb/907477

    As far as the Power button, in XP the behavior is in the Control Panel | Power Options > Advanced tab. What you described is a total non responsive, more than likely, driver issue. If the holding Power button while XP is running normally works then there's nothing to 'fix' but the root freezing problem itself.
  3. XP is set to shutdown when the power button is pressed and it does do that if the OS isn't locked up. Regardless, the issue is not limited to XP. I did a OS upgrade to the new version of Ubuntu and it messed up the X server settings or something so I could only start Ubuntu in low graphics mode. However, at this point, the USB drivers hadn't loaded into Ubuntu so I couldn't click 'OK' to continue in low graphics mode. So, in that case, the computer wasn't really locked up, but a lot of the drivers hadn't loaded yet. Regardless, I held the power button in, and 5 seconds later, nothing. 10 seconds later, nothing. 20 seconds later, nothing. If I am able to boot into Ubuntu normally I can just hold it down and it will turn the machine off.

    The reset button has never worked on my PC case, either that or the motherboard. I doubt it is the motherboard because I RMAed the first one I had after a couple month, got the new one and haven't had any noticeable issues since. So, I can't use the reset button. I've never needed to before.

    I know that if you press the power button the OS is supposed to handle the signal, but if you hold it in it is supposed to do a hard shutdown. However, that isn't doing that. I hadn't noticed this until a couple months ago, but I can't imagine what would change that would make the button turn the machine on, and send the right signal for operating systems to shut down, but won't do anything when the power button is held in.
  4. FYI:
    Windows 7 and Vista (not sure about XP or Linux) have options to change BOTH the hardware or software buttons.

    For example, I set my sister's laptop PHYSICAL POWER BUTTON to Hibernate (not Sleep) when it's pressed.

    The Start Menu power button ("Shut down" in Windows 7) can be set to ANY of the options; that's also why it's no longer "OFF" because OFF is now on of the options which are: "Hibernate", "Sleep", "OFF" and "Standby."

    Hibernate and Sleep:
    I prefer to disabled SLEEP which is a combination of Standby and Hibernation (main memory is on and it also backs up to the hard drive). The problem is that if I enable SLEEP there's no Hibernate-only option which is an issue when moving the laptop as I want it shut down completely but in Hibernation not OFF.

    So I have SLEEP disabled and Hibernate to shut it down (won't turn on accidentally in my bag) and the PHYSICAL power button restores from Hibernation.
  5. Verify your wiring, it seems something's wrong.
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