Comment 4 for bug 401441

Odd, I haven't tried that yet - mine are setup to put to sleep after some fairly long amount
Both monitors are doing it (internal LCD and external VGA LCD).

Still, according to xset q dpms is already disabled.

(I'm also seeing this same problem under xfce - hmm although that might be a red herring since an xlsclients is showing both gnome-power-manager and xfce4-power-manager running;
   gnome-power preferences for 'on ac' shows for display; 'put display to sleep when inactive for: 30mins', 'set display brightness to '100%'
  the xfce equivalent says 10mins to put display to sleep when inactive, 15mins to switch it off.

  The original report was purely under gnome).

Dave