DVI-D - True Digital Video
DVI-D cables are used for direct digital connections between source video (namely, video cards) and digital LCD (or rare CRT) monitors. This provides a faster, higher-quality image than with analog, due to the nature of the digital format. All video cards initially produce a digital video signal, which is converted into analog at the VGA output. The analog signal travels to the monitor and is re-converted back into a digital signal. DVI-D eliminates the analog conversion process and improves the connection between source and display.
DVI-A - High-Res Analog
DVI-A cables are used to carry a DVI signal to an analog display, such as a CRT monitor or budget LCD. The most common use of DVI-A is connecting to a VGA device, since DVI-A and VGA carry the same signal. There is some quality loss involved in the digital to analog conversion, which is why a digital signal is recommended whenever possible.
DVI-I - The Best of Both Worlds
DVI-I cables are integrated cables which are capable of transmitting either a digital-to-digital signal or an analog-to-analog signal. This makes it a more versatile cable, being usable in either digital or analog situations.
Like any other format
The Digital formats are available in DVI-D Single-Link and Dual-Link as well as DVI-I Single-Link and Dual-Link format connectors. These DVI cables send information using a digital information format called TMDS (transition minimized differential signaling). Single link cables use one TMDS 165Mhz transmitter, while dual links use two. The dual link DVI pins effectively double the power of transmission and provide an increase of speed and signal quality; i.e. a DVI single link 60-Hz LCD can display a resolution of 1920 x 1200, while a DVI dual link can display a resolution of 2560 x 1600.
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