Comment 43 for bug 1245474

@Ted, I am not convinced that you are re-assigning the blame correctly.
I have no 13.04 to compare, but I believe that if the kernel (setterm) blanking timeout affected the X screen in 13.04, that was probably a bug rather than a feature. X blanking is controlled by the builtin "screensaver" feature (command line parameter '-s' and xset's parameter 's'), and by builtin "dpms" feature (command line parameter '-dpms' and xset's parameter 'dpms'). The '-s' parameter, by design, just makes the display show black colour, while the latter can signal the monitor to switch to powersaving mode(s). While Xorg is controlling the display, these settings should override the kernel 'setterm' settings.

Display manager starts the X server. It can specify the command-line parameters, and it can modify the settings of the server afterwards. On Ubuntu/lightdm, the command-line parameters are here:

/etc/lightdm/lightdm.conf.d/50-xserver-command.conf

The default is:

xserver-command=X -core -s 5 v

which means screensaver timeout 5 minutes, dpms not set.
You can easily add '-dpms' argument here. Or you can change screensaver or dpms settings from the display-setup script.

The point is that if you do assign some settings in the command line or from the display-setup script, "something" resets them back shortly afterwards. It might be the power manager that tries to do its job, fails, and just resets the dpms. Or it might be something else.