How do you use a dual video monitor with a VGA Y-splitter cable?

According to Radio Shack, using a VGA Y-splitter is as simple as plugging it in to the VGA output port and connecting two monitors. However, there are a few limitations to VGA Y-splitters.

VGA Y-splitters are a great way to display the same desktop on multiple monitors, and they can support up to four monitors at the same time. They are also simple to use because no software configuration is required. While VGA Y-splitters are great for demonstrations, they cannot be used to display different desktops on different monitors. To get an expanded desktop, users must have a graphics card with multiple output ports or install multiple graphics cards.