iMac (17-inch 1GHz), iMac (USB 2.0): About the Video Out Port

The iMac (17-inch 1GHz) and iMac (USB 2.0) computer has a video out port located on the rear of the computer.

1 - Video out	2 - USB	3 - FireWire	4 - Power Plug	5 - Modem
6 - Ethernet	7 - Speaker Mini Jack	8 - Headphone	9 - Audio line in

Figure 1 iMac (17-inch 1 GHz) or iMac (USB 2.0) rear I/O ports

The video out port allows you to use video mirroring with a compatible VGA display using the Apple VGA Display Adapter (M8639G/A). You can also use video mirroring with a television or projector using S-video or composite connectors when you use the Apple Video Adapter (M9109G/A). Video mirroring allows you to see the same image that is on the iMac's flat-panel display on a second monitor, television or projector. This feature does not allow you to extend the iMac desktop with the external monitor. Both the Apple VGA Display Adapter (M8639G/A) and the Apple Video Adapter (M9109G/A) are available separately, and are required to plug in the monitor, S-video, or composite cable.

The video mirroring feature is "plug and play." Simply connect a VGA display to the Apple VGA Display Adapter, television, or projector to the Apple Video Adapter, then connect the Apple VGA Display Adapter or Apple Video Adapter to the video out port located on the back of the computer. When connecting the adapter to the computer, the screen may refresh momentarily as the iMac reconfigures itself for the new video output.

The computer tries to match the resolution of the built-in and external display. If there is no match, the computer changes both screen resolutions and may black out areas on the built-in display in order to compensate for the capabilities of the external display.

In Mac OS X, you can switch resolutions and frequencies for both the iMac flat-panel display and the external display, television, or projector using Displays pane of System Preferences.

DVD Player in Mac OS X allows video mirroring when playing a movie from a DVD-Video disc. You can view the movie image on the external VGA display, television, or projector connected to the Apple VGA Display Adapter or Apple Video Adapter, as well as on the iMac flat-panel display.