My graphics card is a double height card (an ATI Radeon 6950), and on the first level, it has a DVI port and an HDMI port, and on the second level, just a DVI port. I had been using the DVI port on the first row for my 24" Asus monitor.
When I got the new monitor, it only came with a VGA to VGA cable, which my graphics card does not support, and the new monitor does not support DVI.
So firstly, I had to go and buy an HDMI cable.
That done, I changed the Asus monitor to use the DVI port on the second row and plugged the Samsung into the HDMI on the first row.
Back in Windows 7 Ultimate, I could select either monitor individually, though the Samsung appeared blurry and the image didn't go to the edge of the screen. When I tried to extend my desktop across both screen, I would get the error: "Unable to Save Display Settings".
Of course, I went straight to Google, and found links such as the following:
- Unable to Save Display Settings;
- Unable to save display settings and Multiple Monitors;
- Problem with dual monitor settings. "Unable to save display settings"; and
- SOLVED: Unable to save display settings, windows 7, multi monitor setup
These posts, sometimes answered by someone from Microsoft, or at least an MVP, focused on notebook-related problem, requiring an edit of a non-existent key in the registry, or changing resolutions, complaints about Catalyst Control Center or nVidia's equivalent, or just other things that turned out to not be relevant.
Lots of messing around, and frustration led me, in the end to discover what was actually a very simple problem. Considering the number of people who could not resolve this problem using the "standard" way on these posts, I hope the solution to my problem will help others.
In the end, all I needed to do was move the Asus monitor (the original one) back to its original DVI port on the first row on the graphics card. I made a bad assumption, and it took me around an hour to realise it.
Also, just to help out anyone else who has the issue with a new monitor not extending all the way to the edges of the screen, I was able to fix that on one of the settings pages in Catalyst Control Center, where there is a slider for overscan/underscan. It seems like a very CRT-related bit of functionality, but it wasn't set to its maximum of 0, so once I moved it there, the screen was at the right size.
Let me know if this helps you solve your dual monitor / multiple monitor setup problem.