Comment 26 for bug 34233

I've had this problem ever since I got my LCD monitor (HP LP2065). The problem has been the same for edgy, feisty, gutsy, and hardy. It may have something to do with the Avocent SwitchView 1000 KVM between my desktops and my monitor, however my Windows box can put the display to sleep just fine regardless of how I have Windows setup to control it. I suppose it could also be a quirk with the graphics card in this box ("nVidia Corporation NV44 [GeForce 6200 TurboCache(TM)] (rev a1)").

After experimenting with the DPMS method used by gnome-power-manager, I was able to get it to work by using the "standby" method for:

/apps/gnome-power-manager/backlight/dpms_method_ac

I would try experimenting with all three settings for your particular cases. I restarted gnome-power-manager between each test, but this may not be necessary. Note that you have to actually wait for the screen saver to start before gnome-power-manager sets the DPMS settings for the power savings timeout (1 minute screen saver + 1 minute display sleep in my case). When looking at the output of "gnome-power-manager --verbose --no-daemon" for each method with a 1+1 minute timeout, I see (once the screensaver starts):

"BACKLIGHT parameters 60 0 0, method '2'" for "standby"
"BACKLIGHT parameters 0 60 0, method '3'" for "suspend"
"BACKLIGHT parameters 0 0 60, method '4'" for "off"

In my case, my monitor/KVM combo only responded to the "standby" method. YMMV.