Connect two ADC displays
There are several ways to use two displays with "Apple Display Connector" (ADC) ports. This may not be easy or even possible, depending on the computer you want to use. Under the right conditions, though, this setup could support Video spanning and/or Video mirroring.
The ADC connector supplies digital video for the computer display as well as USB and power. Thus, video cards that support ADC must power the monitor that is connected to them. As of this writing, no Apple ADC monitors come with external power supplies.
All of Apple's current ADC-based displays also require digital video, which means you cannot use them with a VGA connection (which is analog only).
To make this dual ADC display setup easier, you should have a Macintosh computer that already has one ADC port on the video card . Typically, this means you need a later model Power Macintosh G4 (or newer) system. Later model Power Mac G4 systems supported ADC with their pre-installed video cards; earlier computers do not provide enough power to the AGP video card to drive an ADC display. (We know of no PCI video cards that can drive an ADC display on their own.)
You need to make sure that the combination of video cards you use will have enough VRAM to drive the displays you are attaching. Even with enough VRAM, certain video cards may not be able to drive an Apple ADC-based display.
The quick (but not necessarily easy, as you may have guessed by now) options involve:
- A Power Macintosh G4 (or later) that has two digital video ports on its AGP video card, and can drive one monitor on each. (Not all of Apple's bundled cards can drive two displays independently, even if they have two monitor ports.)
- A Macintosh with one AGP video card that supports ADC, and another PCI video card that supports DVI.
In either case, you hook one ADC-based display up to the ADC port on the AGP video card in your Macintosh. You hook the second ADC-based display up to a DVI port, either on the AGP card (if it supports two displays, and not all do) or on the PCI card. To connect an ADC display to a DVI port, you need an adapter like the Apple DVI to ADC adapter or a third-party equivalent.
The DVI to ADC adapter must inject power. This is not a simple adapter, then, but the rough equivalent of a video adapter plus an external power supply.
We know of no way to connect two ADC-based monitors to Apple laptop systems (through September 2003 models, at least) for two independent external displays.