Dual Monitor Video Card
If you’re like me, you going to want to have more video desktop space at certain times. Even if your computer or laptop has two video ports, sometimes just being able to add another low update rate video screen to show extra web pages or text can be very helpful. When it comes to dual monitor video cards, USB is definitely the way to go because you don’t have to open up your computer to add a PCI card. The downside is the USB bus is not going to transfer at the rate of your computers internal bus. Also some specialized software like DVD play back may have trouble using these unusual video devices created by the custom USB drivers.
There are some product choices for these particular types of USB adapters. Such a device is in theory a video device but not in the same class of the more standardized video capture USB class that you would have with webcams and USB video inputs. So default drivers written by the operating system can’t be used. Instead, a customized driver has to be written for the operating system so that the dual monitor video card device appears as an extra video screen. Because of this, don’t expect these devices to work under Linux unless the manufacture specifically creates a driver. To a lesser extent Apple OSX might or might not have drivers.
A good example of a dual monitor video card is the Matrox Dualhead2go. This device allows you get two extra desktop screens including the exiting output from your notebook or desktop. For more money there is a TripleHead2go version with three VGA outputs. Matrox has written drivers for the devices for windows 2000, XP, and Vista. The Mac OS drivers show OSX 10.4 and 10.5. They also list Linux drivers but I seem not to be able to find a link to download those on their website, so it is possible that it is a open source project found elsewhere.
Another cheaper device is the StarTech USB2VGA adapter. There seems to be Windows 2000, XP, vista, and window 7 drivers written for it, and creates one extra VGA output screen per adapter. Interestingly, the USB driver is written to run up to five additional displays for more USB2VGA devices you plug in. You can also just mirror your existing display if you want. Don’t expect to use these external displays for video streams. You can only do so much with the USB speed and CPU load with these types of dual monitor video cards. No Apple OSX drivers. StarTech also has a DVI version called USB2DVI, which is more expensive.
Here is an example video of using more than two monitors: