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Matrox's DualHead/TripleHead

Manufacturer Matrox
Model DualHead/TripleHead
If two is good, what about three?
Matrox supported running multiple monitors with a single graphics card long before it became cool, let alone virtually standard. In fact, in the area of multimonitor functionality, Matrox's offerings have traditionally been considered the standard by which others are measured. Matrox added a new wrinkle to multimonitor graphics when it released Parhelia, which brims with Matrox's famous DualHead multimonitor goodness, but also adds TripleHead, or support for a third screen.


Matrox's Parhelia: Niche king

We covered Parhelia's features and performance in our initial review, so read that if you're interested. I'll be concentrating, of course, on the elements of Parhelia's hardware that matter for multimonitor applications. Of particular note is a set of 400MHz 10-bit RAMDACs. With these, you don't have to sacrifice signal quality to run a second monitor, and you'll still be able to indulge in 10-bit per channel GigaColor goodness. Dual DVI outputs with resolutions up to 1600x1200 are supported, if you're lucky enough to be sitting in front of a couple of massive flat-panel screens. However, there are some resolution and display limitations when you get into three-display setups that I'll explain a little later.

As we saw previously, Parhelia is capable of 3D acceleration across all three screens, with both DirectX and OpenGL. For some time now, Matrox's 3D performance hasn't been on the same level as competition from ATI and NVIDIA, but Parhelia's ability to extend 3D acceleration to three screens is unique. For some 3D professionals, the ability to extend a workspace onto second and third monitors may be more important than the raw pixel-pushing performance of the graphics card itself.

Wraparound triple-screen displays could be very useful for CAD applications, but Matrox is also trying to push Surround Gaming for, you guessed it, 3D-accelerated gaming across multiple screens. Personally, I'm not convinced there's much value in Surround Gaming yet. Current RTS and simulation games may be able to get away with meaningful Surround Gaming in the real world, with tertiary screens used to display alternate views, cockpit controls, or a bigger view of the battlefield, but first-person shooters offer little more than a wider field of view at the moment. Because TripleHead is unique to Parhelia—a card whose market penetration isn't all that spectacular in general, let alone among gamers—it's unlikely many game developers will specifically support three-screen Surround Gaming for anything more than an expanded field of view. I do hope the feature will open some eyes to the potential of meaningful multi-screen gaming, even if developers start out only targeting two-screen configurations.


At last: dual DVI

Matrox's Parhelia comes with dual DVI ports right out of the box. But how do you squeeze three monitors out of only two DVI output signals?


The keys to TripleHead

With an adapter. Actually, a couple of them. TripleHead is quite a bit more limited than DualHead. If you want to run TripleHead, you can only use one DVI monitor, and you're mostly limited to running a stretched desktop with a uniform screen resolution of 1280x1024 or lower on each of the screens. If you want to extend your Windows desktop area across all three screens, those screens can't run independent resolutions, refresh rates, or color depths.

TripleHead's three-screen desktop limitation is a little annoying, but an alternative three-screen setup makes those limitations a lot easier to swallow. Parhelia has the capability to run two monitors in a DualHead configuration (including independent refresh rates, resolutions, and color depths) with a third screen reserved for special features like zooming and Matrox's DVDMax. This configuration should be especially compelling for content creation professionals who regularly use zoom and DVDMax features, since it leverages a third screen to take care of those special features while retaining the flexibility of an independent DualHead desktop.

Since TripleHead is brand new and competition for three-screen setups is sparse, it's hard to really fault Matrox for TripleHead's initial limitations. Quite simply, no other card in this class can drive three displays at once. Still, I'd like to see TripleHead capable of handling a three-screen extended desktop with independent refresh rates and resolutions. Three DVI outputs would be nice, too.



In DualHead mode, if you're running screens with independent refresh rates, color depths, or resolutions, Windows sees multiple, independent displays. A stretched desktop isn't an option in this configuration, but you can still extend your Windows desktop to a secondary display. DualHead's extended desktop is also capable of displaying different resolutions, refresh rates, and color depths on each screen.