Duplicate a screen on multiple monitors
Jim Martin shows how to duplicate a computer’s screen, so that it can be seen on different monitors
Windows makes it surprisingly easy to work with multiple monitors, but in most cases you’ll be working with two, or perhaps three at a push. Two is great for having several applications visible at once, while three is great for gaming – if your graphics card is up to the job. Here we’re using Windows 8.1, but the process is almost identical in Windows 7.
Duplicate screen on multiple monitors
When you first connect a second monitor, Windows should detect it and automatically duplicate the screen on both displays. This is the case regardless of whether you have a PC with two monitors or a laptop with a screen or projector attached.
If you don’t see an image on the second screen, look for a function key on the top row of keys on your laptop which shows two monitors. Press the Fn key and the appropriate function key (F5 on the laptop below, for example) and it should toggle through the various configurations: laptop display only, laptop and external screen, and external screen only. You can also try pressing the Windows key and P at the same time for the same effect.
If you still have no image, go to the Windows desktop, right-click and choose screen resolution. If you see only one screen in the dropdown Display list, try clicking the Detect button to force Windows to scan for the second screen. If it has detected it, you can use the other options in this window to choose how Windows deals with multiple monitors.
Since you want to duplicate the screens and have the same image on both, make sure ‘Duplicate these displays’ is selected in the Multiple displays drop-down menu (see bottom-left image).
Note that duplicating displays is often a compromise if the screens have different resolutions or aspect ratios. For example, if you hook up a 1024x768 projector to a laptop with a 1366x768 screen, both will run at 1024x768, and you’ll end up with black bars on the left and right on your laptop screen.
Extend the desktop across multiple monitors
Assuming you’re not using a projector, which is when it makes sense to duplicate the screen, then you probably want to extend the desktop to have different things on each screen. To do that, choose ‘Extend these displays’ instead of ‘Duplicate these displays’.
You can select a monitor in the diagram at the top and drag it to the position it’s in on your desk. Here we’ve put the second monitor on the left of the laptop because it defaults to the right. You can move the smaller screen up and down, too.
You’ll also notice you can select different resolutions for each screen, but you have to select each screen in turn. Only one of the monitors can be your main display. In Windows 7, that means it will be the only monitor with a task bar and start button. In Windows 8.1, you get those on all screens, but only the notification area and clock on the main screen.