I had several issues with gnome-power-manager and acpi-support.
Both are base on the acpid daemon for power management. Acpi-support is a convenient package of scripts to configure the power management.
It is bundled in many distributions, including Ubuntu and Debian.
The problem is that it does not cooperate very well with gnome-power-manager. As a result, I had many small but anoying issues.
The most anoying was, that after a suspend / hibernation, gnome-power-manager was not able anymore to turn off the screen for power saving. Workaround : kill it and start it again. Not good !
Pretty annoying, especially since I stopped using a screen saver with my LCD screens…
So I tried a new alternative to acpi-support : pm-utils. This is another collection of scripts, attached to the Freedesktop.org project, as gnome-power-manager : the integration with Gnome should now be much better, shouldn’t it ?
$ aptitude remove acpi-support $ aptitude install pm-utils
Now we copy the default configuration file to the /etc directory. All files will be parsed, but the one in /etc has the priority if you change a value :
$ cp /usr/lib/pm-utils/defaults /etc/pm/config.d/
With my laptop, I had to edit a line to activate suspend-to-ram, so that it looks like :
S2RAM_OPTS="-f -a 3"
And that’s it ! I did not go deeper, but there are already much fewer issues with gnome-power-manager (though it still need some work).