XF86PowerOff

http://crunchbang.org/forums/viewtopic.php?id=28461

xmodmap -pke | grep PowerOff

keycode 124 = XF86PowerOff NoSymbol XF86PowerOff


~/.config/openbox/rc.xml:

<keybind key="0x7C">
    <action name="Execute">
        <command>oblogout</command>
    </action>
</keybind>


It still may be worth adding 'acpi=force' to the list of kernel parameters.
If that doesn't work try 'apm=off acpi=force'

ACPI:
https://wiki.archlinux.org/index.php/Power_Management

acpid
https://wiki.archlinux.org/index.php/Acpid
http://askubuntu.com/questions/334168/my-power-button-doesnt-work-under-lxde-how-can-i-fix-this