DVI, or Digital Video Interface, comes in a variety of connections. These are typically white and found on the backs of both monitors and video cards. There are two primary types of DVI connectors:
You'll notice the DVI-I connection has four extra pins. Since DVI-I carries both analog and digital signals, these four extra pins are what carry that analog signal. DVI-I connections are common on video cards as they offer more ways to connect to a monitor: Either through a digital DVI connection, or through an analog VGA connection using a DVI-I to VGA adapter (these typically come with the video card at the time of purchase and look like this)
In addition, there are both single-link and dual-link DVI connections. If you have one of our XL-series PC gaming monitors, you'll want to use either a DVI-D Dual Link cable, or a DisplayPort cable in order to achieve a 120-144Hz refresh rate. All of our monitors use DVI-D ports as an input.