Red Green Blue Video Graphics Array and Digital Visual Interface ports are used by computers to send video content to connected monitors. The two standards use different ports to connect devices, vary in image quality and support different analog and digital transmission standards.The VGA connection standard is the older of the two and has been replaced by technologies like HDMI, Display Port and Thunderbolt in addition to DVI.
Number of Ports
Both RGB VGA and DVI connections use a singular cable device; however, RGB uses more ports than cables. DVI cables feature identical connectors on both ends: both devices have a single port. Some computers may feature multiple DVI ports to connect to multiple monitors. RGB VGA is a subset of the VGA connection standard that breaks up the video signal into three to five individual cables. RGB VGA devices feature a single VGA port on the computer but have three to five color-coded RGB VGA ports on the monitor. Standard VGA bundles the wires into a single cable whereas RGB VGA breaks the wires apart to reduce interference and improve image quality.
Connection Port Design
Both DVI and RGB VGA ports feature the female connection side and use pin and socket connections. DVI ports look the same on both the computer and monitor, whereas the computer features one standard outgoing VGA port and the supporting monitor features three unified RGB VGA ports. The DVI and VGA ports both resemble upside down trapezoids. DVI ports are twice as wide as VGA ports and are white by default whereas VGA ports are blue by default. The RGB VGA ports on the monitor are colored red, green and blue with optional black and white connectors. Each RGB VGA port connects to the corresponding color-coded cable. The RGB VGA ports are circular sockets with a raised pin used to lock cables in place.
Analog and Digital Signals
VGA and VGA RGB connection ports only support analog video signals, whereas DVI connection ports can support either or both analog and digital signals depending on the port type. Digital-only DVI ports have a single wide, horizontal socket on the left side of the adapter. DVI ports that support digital-only or both analog and digital feature two smaller sockets both on top and below the horizontal pin with four sockets on the right side of the port. Some lower-resolution supporting DVI ports will be missing two columns of pins from the center. A computer that supports analog DVI output can be connected to a DVI-to-VGA to output over RGB VGA.
Image Quality Differences
RGB VGA ports receive a converted digital-to-analog signal that can suffer image quality degradation when being displayed on a monitor. DVI ports send and receive a digital signal directly from the computer that does not need to be converted and does not suffer image quality drops. DVI ports can update on-screen content faster than RGB VGA because there's no time lost in the conversion process.
- Hardware Secrets: Video Connectors Tutorial: Red, Green and Blue (RGB)
- Hardware Secrets: Video Connectors Tutorial: Digital Video Interface (DVI)
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- EPanorama.Net: VGA to Workstation Monitor FAQ Making the Connection to VGA Card
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