So you want to drive two external displays from your shiny new unibody macbook pro…well, I’ve got good news and bad news. The mini-displayport doesn’t have the juice to drive multiple external monitors, even mated to a solution like the Matrox Dualhead2go which worked so well with the previous DVI-equipped macbooks. Enter theTritton SEE2 Xtreme. Though it’s very choppy when dragging windows on the screen, generally the video quality is very good, and it’s only GPU-intensive motion that causes issues. The device works with a few hiccups, such as issues when waking from sleep on the usb-driven monitor, but it’s the only solution available, so… There are other usb to DVI adaptors on the market, but no other can handle 1920×1280 resolution. If you’re driving a pair of 24″ displays or larger, this is the one you have to get. Also, Triton, the company behind this device, released a updated driver recently that solves the previous issues that occured with the OSX 10.5.6 update.
The Apple Dual-link adaptor: Apple did the Mac community something of a disservice when they named this item, as it’s extremely misleading. This cable DOES NOT allow you to connect two external displays to your macbook. Rather, it uses two cables (one USB and one mini-displayport) from your computer to boost the power available from the mini displayport so that you can drive 30″ monitors. It’s really a shame that the mini-displayport doesn’t have the juice to power the largest monitors (or, indeed, to power dual external monitors), but such was the tradeoff for the MDP’s small size, I guess. One other use for this cable is, if you have the Matrox Dualhead2go, this will boost the output of the mini-displayport enough that you can run dual external monitors from it…BUT it still doesn’t have the juice to run dual 1920×1280 externally; it can only run them at 1680×1050 each. Unless you really want full-motion video (or action game graphics) on both external monitors, you should go with the See2Xtreme, above.
The Matrox DualHead2Go Digital Edition an excellent device, but alas, as mentioned above it will provide no joy on its own if you have a computer with a mini-displayport. What sets this apart, both in performance and price, from the See2Xtreme above is that it basically contains an external graphics GPU within itself, and it doesn’t rely upon USB to output to your display (though it does use a USB to draw the power to drive itself). If full-motion graphics are your requirement, rather than ultimate resolution for still graphics, this is the device you want. You will need to pair this with the Apple dual-link cable above to get the required juice to run two monitors, and then only up to 1680×1050 apiece, but the matrox won’t hold back your frame rates the way the usb-based solutions do.