We don't all have high-powered PCs that can support bank upon bank of monitors. Some of us are trapped in a single-display hell, clinging to our miserable existence in the hope that, one day, we too may be able to have a spreadsheet open on one screen and a Web browser in another.
Even if you decide to buy a graphics card that supports more than one display, you won't find it easy to install it in many PCs, even ones of the desktop variety. That's when external USB-to-DVI or USB-to-HDMI converters come in handy. Such devices can turn a USB socket into an extra monitor output.
Atlona's AT-HDPiX2 is a USB-to-HDMI converter that will appeal to people with new, higher-resolution monitors. It costs about £140 online.
It's beyond the scope of this review to go into tonnes of detail about how this kind of system works, but we should explain the basics, so you can understand the limitations of the hardware.
Video destined for your secondary monitor is sent via USB. Unlike video that travels via HDMI, DVI or VGA, this signal is quite highly compressed, and also uses an MPEG-type algorithm which only sends information about the area on the screen that is actually changing. It all works very much like MPEG in TV broadcasts, and can reduce the total bandwidth needed to a level that's within the capabilities of USB 2.0.
In terms of day-to-day use, the AT-HDPiX2 is just like any graphics card. It appears, together with your main graphics card, in your computer's display manager, just as two graphics cards or a dual-headed graphics card would. This means you can set the screen orientation and resolution as you wish, as well as place your second monitor to the left or right, or even above, your existing monitor.
The AT-HDPiX2 can drive monitors with a 1,920x1,080-pixel resolution. If you're still using square screens, then an output of 1,600x1,200 pixels can be achieved too.
If you need plenty of monitors, you can use up to six AT-HDPiX2s with your PC. Mac users are restricted to four AT-HDPiX2s for some reason. Be aware that there's no official Linux support, although some user-generated drivers do exist. While impressive, they don't work as well as the drivers for the Windows and Mac platforms.