so I had everything working fine - Monitor + TV connected via s-video as dual screen. However I recently cleaned my PC, disconnected everything and after putting it back together, it doesn't work..
Before both the monitor and the TV used to show the POST message, but now, only the monitor shows this. Its like, the PC doesn't pick up the s-video anymore. I can go into 'screen resolution' and try to extend the display onto the tv but I get this annoying error message that says "unable to save display settings".
If I select to use the TV as a single display, this works fine so its not a cable problem or source problem. I think it could be something to do with the tv driver / device not being picked up but I don't see an obvious way to fix this in device manager.
Okay I fixed it finally. After much messing around with settings, new drivers, etc, none of that worked.
The 2nd display wasn't showing when I booted the machine up but I knew it should be. I can't be certain what exactly I did but try any / all of these:
1. Re-seat the video card into the PCI slot.
2. Change your primary display to the second output on your card (if you have one)
I put it all back together, booted and immediately the slave display showed the boot message. The "unable to save display settings" error message is misleading because it implies that your problem is likely to be software, where as for me, it was hardware. Lots of threads on the internet about this. Fiddle with your hardware until you get your displays showing the boot screens.