Dual monitors, secondary monitor on/off intermittently

I think this is the right place to ask this.

I have two monitors connected to the ATI Radeon HD 2600 XT graphics card (it has two DVI connections). With both monitors on everything works fine. Windows remembers which apps I have open on which monitor and so on.

However, sometimes I turn on only one (the primary) monitor. In this case Windows somehow still thinks that both monitors are there, so the apps which would open on the second monitor still do so, i.e. I can't see them when I start them, and the mouse goes easily beyond the active monitor.

Now, the second monitor is completely off - it has a real power switch. But it's possible that it still has some voltage through the connector so that Windows - or the graphic card - detects its presence. I have not tried to unplug it but maybe I should do that as well.

So finally my question - is it possible to make Windows aware that the second monitor is not in use and only extend the desktop when the second monitor is on and do that without restart/log off?

Thanks for any suggestion.

If it's plugged in when you boot, Windows will assume it's in use and available...

No known Windoze workaround... connect multiple monitors, Windoze will 'think' they're all turned on and working - however you might find some third party software (like Ultramon for example) might be able to correct the problem...

Thanks for the information Qdos! Oh well, I thought I could get away without third-party software ...

Post any third party solution you end up using, lots of people are using more than one monitor and might benefit... and thanks very much for the +rep too...

even though you have not powered the slave monitor its still listed in the control panel as ''extended desktop''

& even if it did disable the desktop extension when you powered the 2nd monitor down, it would not transfer slave app desktop positions to the primary monitor....

Actually it turns out that Catalyst Control Center does the trick, sort of. I did not have it installed before, but today I was downloading the latest drivers and decided to give it a try. There is also some multi-monitor managing software they call Hydrovision, but I have not tried that one yet. Maybe it will improve things. I will post an update if this will be the case.

So, right-clicking on the ATI CCC icon in the system tray I have a menu with both of my displays besides other items. Each of the displays (although both named identically after the graphics card, go figure) have their own sub-menu and there for the secondary monitor I have an option of disabling it. If I do that, then applications that would open on the secondary monitor before start opening on the primary one.

That's good news - at least I am not losing application if I only run one of the monitors. Of course, I have to click on the menu to achieve that, but that's better than nothing.

The bigger problem is - once the secondary monitor is re-enabled, the applications I want there would not suddenly start there as they will remember their last position on the primary monitor.

So, the CCC solves the biggest problem I was having - losing applications completely (i.e. if they would start on the secondary monitor while it's off - I'd not see them and have no access to them). This is not the same as automatically detecting the second monitor and arranging the desktop accordingly. I will see if Hydrovision may help with that before looking for something like Ultramon, as Qdos has suggested above.