No monitor power control function since kde4.x/8.10

[dalesd]

There's an option in the Power Management in System Settings - go to the Edit Profiles section, select whichever profile you want to lock the screen in (as a desktop system, I'm only using the Performance profile). The "When the system is idle for more than..." option is essentially the same as the screen saver lock.

Maybe I'm still a KDE noob, but I can't find the section you're describing.
From the K menu I go to Applications -> System -> System Settings, and there's no power management there.

[txcrackers]

It's in 4.2 - for 4.1.x I believe you have to install "powerdevil" (you might want to research that one).

[johnnyhop]

Try installing kpowersave. It worked for me.

I still have to disable the screen saver in System Settings>Desktop>Screen Saver, uncheck Start automatically. Is there a winning combination of settings between KPowersave and System Settings that enables screen saver then monitor standby?

Late April upgrade to 9.04 problem persisted. Late May did clean install of 9.04, now both screensaver and monitor power control work!

[johnnyhop]

With the online distribution-upgrade to 9.04 neither screensaver or monitor power saver settings would have any effect. A clean install of 9.04 fixed both screensaver and power settings. Just goes to show you, a clean install while more trouble, just plain does the Ubuntu experience more justice and satisfaction.

[at165db]

Thanks, this also fixed my issue. I'm going to miss Asciiquarium!

So here is a quirk, I've not tested yet. We have essentially 2 different places to set the display power management.
One is in the System Settings->Advanced->Power Management->Edit Profiles->Screen.
The other is System Settings->Display->Power Control.

I hope the lowest time wins.