DVI Simplified

What is DVI?
DVI, short for Digital Visual Interface, is a video interface standard on the latest digital display devices such as flat panel LCD computer displays and digital video projectors. It was developed by the Digital Display Working Group (DDWG), an industry consortium. It is designed for carrying uncompressed digital video data to a display but does not carry audio as HDMI does which is it's primary disadvantage in the format wars. It is partially compatible with the High-Definition Multimedia Interface (HDMI) standard in digital mode (DVI-D), and VGA in analog mode (DVI-A).

DVI comes in several versions. DVI-D is the all digital version. DVI-A is the analog version and last but not least there is DVI-I which is an integrated version that will allow the transmission of both digital or analog signals.
As if that isn't enough, there are also single link and dual link to consider. Single link cables use one 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. In practical terms, 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.

Like their analog VGA cousins, DVI connectors include pins for the display data channel or DDC. DDC2, a more recent  version of DDC allows the graphics adapter to read the monitor's extended display identification data or EDID. If a display supports both analog and digital signals in one input, each input can host a distinct EDID. If both receivers are active, analog EDID is used.

The maximum length of DVI cables is not included in the DVI specification since it is dependent upon bandwidth requirements. In general, cable lengths up to 15 feet will work for displays at resolutions of 1920 x 1200. This resolution will work even up to 33 feet if a larger gauge, premium cable is used. Cable lengths up to 50 ft can be used with displays at resolutions up to 1280 x 1024. For longer distances, the use of a DVI extender or booster is recommended to retain resolution and minimize signal loss.

Common Applications
DVI is referred to as successor to VGA although HDMI and Display Port are still battling for that title. DVI connection can be found on the latest computer and video equipment including laptop and desktop computers, computer monitors, LCD and LED flat-panel displays, video and data projectors and much more.

How to choose the right DVI Cable for your application
First you need to determine the DVI connection type you are dealing with. Below are the common DVI connections.
Note that their pin-outs are all different so be sure to review your equipment and/or manual closely to be sure you are purchasing the right cable type.

DVI Connection Types

If one or both of the connections are DVI-D, a DVI-D cable (most common) is what you need. If both connections are DVI-I, you may use a DVI-I cable or DVI-D cable. If one or both of the connections are DVI-A, you need a DVI-A cable. If one connection is DVI and the other is VGA, and only if the DVI connection is analog-compatible, you can use a  DVI to VGA cable or a DVI to VGA adaptor. However if one of your connections is analog and the other connection is digital, there is no cable that will allow you to connect them. You will have to use a DVI to VGA converter in order to bridge the two formats.

Performance Levels
Once you have chosen the correct type of DVI cable you need, your next decision is what quality grade to purchase.

While the signal itself is digital, it is still being transmitted over an analog medium so cable construction will play a role in your resolution output-especially over long distances. It will also have an impact on cost as more copper for larger gauges and more or preferred (and more effective) shielding methods will add to the purchase price. Look for at least double shielding and braided shielding over spiral or foil shielding as a general rule. Also look for a flexible jacket for increased durability.

That said, do not let anyone try to justify spending $50 or more for a short length DVI cable as retail brands often do as you are throwing your money away. Fancy all metal connectors and braided jackets are ploys to dramatically increase the price with zero performance benefit. Expensive blister packaging is not only bad for the environment, it adds several dollars of cost to the product. On the other end of spectrum, use common sense and be very wary of anyone telling you that you can get professional quality for $2.50 either. That bargain won’t seem as attractive when you have to endure the additional aggravation and expense of downtime and a second purchase to replace a poorly made cable from some internet importer selling cheap knock-off cables from China

Standard DVI CableStandard DVI cables are usually 30 or 28 awg with a ferrite core to supplement the lower-cost shielding method. These are perfectly fine for general purpose and short runs 15ft or less.

Premium Professional Grade DVI CablePremium professional DVI cables usually are constructed of 28 gauge or larger construction and feature double shielding which helps protect against EMI and RFI interference.

Super Premium DVI CableSuper Premium DVI cables usually feature a larger 24 gauge construction and can sometimes also feature triple shielding. These are perfectly suited for heavy duty applications and longer runs above 15ft but are overkill for short non-critical applications.