I have a fresh install of Ubuntu 9.04 (jaunty) on my iMac (specifically iMac8,1, aluminum). In gnome-screensaver-preferences, I have the screensaver set to come on after 1 minute, and then in gnome-power-preferences, I have "put display to sleep when inactive for" set to 2 minutes. However, after 2 minutes, my screensaver keeps on running.
I'd like to know if anyone has a solution for how to get the iMac monitor in Ubuntu to automatically sleep, what packages I may need to download, or what the relevant log files would be to see if the event is getting trigger and/or what errors are coming up. If there isn't hardware support for sleeping an iMac monitor in Ubuntu, I'd appreciate that bit of info too.
EDIT: I'm not on the system right now, but I've found that the command "xset dpms force off" should force the monitor to sleep. If it works, then I need to figure out how to get the preferences to put the monitor to sleep. If not, it means I have a hardware issue to figure out. I'll update with more info when I get to try it.