As stated above if you have only two monitors, or three (or more) that do not share a common resolution size--meaning that they do not have matching aspect ratios--then you will not be able to take advantage of NVIDIA Surround or AMD Eyefinity. The option may seem like it is available, but you will quickly realize it will not be usable.
The option to extend your desktop across all of your screens will still be available, just not for games. And many people who utilize more than one monitor often do so for gaming purposes.
The following steps should help you extend a game screen across all monitors easily:
- In the game settings, ensure the option from full screen is changed to windowed.
- When the game either is loading up, or when it starts, press CTRL+ALT+DELETE to access the task manager. DO NOT MINIMIZE THE TASK MANAGER!
- Go to the edges of the game screen and pull it across to one of your other screens.
- If you have only two monitors, then you are done. If you have three, repeat steps #2 & #3 for your other screens.
- Repeat steps #2 & #3 if you have to elongate the game screen to reach the top and/or bottom of your screen(s). If the screen already reaches the top and bottom, ignore this step.
- You can now minimize the task manager, or click the game screen, to go back to the game.
Note II: If you do not have a windowed option, search Google as many people have workarounds to access this option in certain games.
If you are really lazy, you can use either Actual Multiple Monitors, or purchase a program called UltraMon. Both of these add a button next to the minimize button of a window that can automatically stretch that window across all screens perfectly. The Actual Multiple Monitors is free (for 30 days), but for whatever reason does not stretch to the bottom automatically if using external displays with differing resolutions. UltraMon will stretch both across and below automatically.
The only downside is that the screen is obviously not quite full screen since it is in windowed mode. However, the trade off is that the game will technically be slightly smaller than full screen resolution, giving a (very) marginal boost in frame rates since it works that much less to render the game.