Dual Display Comparison - February 2001

Some Drawbacks

Despite all that using a second display has going for it, there are naturally some drawbacks to having two displays instead of one. On the most basic level is the issue of space. Naturally, two 15", 17" or 21" monitors are going to suck up a lot more desk space than a single one. Even the combined size of two relatively small 14" monitors often turns out to take up as much space or even more than a 21" single monitor.

Next on the list of drawbacks is the downside to applying a dual monitor solution to two different types of displays. Ideally, a dual setup should be run on identical displays, allowing not only images to appear the same but also minimizing the amount of space between the two monitors. In our tests we ended up using a 15" LCD display paired up with a 19" traditional CRT. This proved to be a mixed blessing; although we were able to take advantage of the features mentioned above, it was very difficult to get images to look the same on both monitors. In addition, the use of two different displays produced a desktop that was at two different levels. Although running individual applications in this setup did not provide a problem, as the application was typically maximized to a single monitor, when running an application in full screen mode where it spanned both monitors, the varying heights produced undesired results.

The reason that this is important is that many of the home users out there looking to configure a dual monitor setup are currently thinking about using a new, large display as the primary display and an older, smaller display as the secondary display. This does not produce any problems or provide any limitations for the most part, except when trying to view an image that is spanned across both monitors. The images of an application spanned in the previous section tend to be misleading, with the two screens not producing a clean seam.

Another downside is that current dual display setups are limited to 2D. In the case of the solutions out there now, only the primary display gets hardware 3D acceleration. This means that on the second display, no 3D can be outputted, limiting what you can do on the second display. The main limitation with this is that 3D games are currently off limits for dual display games. Although this may be a give in for many, considering very few cards have the fill rate to power two monitors at any reasonable resolution anyway, all those dreaming of dual monitor Quake III will just have to wait.

The final limitation deals with the operating system Windows 2000 itself and not the dual display technology. Windows 2000 has a limitation that prevents two separate monitors running off the same card from running at different resolutions. With identical monitors this is not a problem, but as you can imagine having an old 15" and a new 19" monitor would result in quite a problem when you are forced to run both screens at 800x600x32 so that you can see images on the 15" monitor.

That essentially covers the main limitations facing dual display solutions on the market today. Naturally, each product features problems, as well as nice features, of their own in an attempt to outshine their competitor. Let's see what is out there in terms of dual display video cards.