I've just found out that my external monitor remains on for quite a while in the suspend and off modes (xset dpms force off). The only one that it accepts is standby. Then it turns off right away. And the internal one as well. So that's fine for me. But good to know, isn't it? ;-)
And btw. if you want to use it in a script you have to issue the xset command twice and sleep in between for about 6 seconds. Otherwise they're not really off. Don't ask me why...
