DVI vrs VGA

[Skuzzy]

A digital signal will not be affected. 

Actually that is not true.  A digital signal is more apt to produce ring-back on the cable making the length of the cable critical.  If the cable length is a harmonic of the switching frequency of the signal, it is very possible to trigger false signals, or to cancel out good signals depending on the switching level of the signal.

Also due to capacitance and resistance it is very possible to get a cable too long, which will degrade the level to a point where it may not be recognized at the other end.

[Masherbrum]

Actually that is not true.  A digital signal is more apt to produce ring-back on the cable making the length of the cable critical.  If the cable length is a harmonic of the switching frequency of the signal, it is very possible to trigger false signals, or to cancel out good signals depending on the switching level of the signal.

Also due to capacitance and resistance it is very possible to get a cable too long, which will degrade the level to a point where it may not be recognized at the other end.

Agree, however the Digital Signal will be "less effected" than an Analog VGA signal.

[Skuzzy]

To some degree.  Analog signals are pretty robust and not subject to some of the issues a digital signal are, but an analog signal is more susceptible to noise/EMI interference than digital signals are.

In a noise/EMI free environment, analog is actually better than digital as far as being robust is concerned.

Take a look at all the analog buses in a computer today (and more on the way).  PCI-E, SATA, USB,...  These are all analog buses carrying digital data.

[gyrene81]

Agree, however the Digital Signal will be "less effected" than an Analog VGA signal.

That is true depending of course on the source as well as the cable quality. DVI specs as of right now state a maximum length of 10 meters although with the higher performance video cards 40 feet is easy...those specs are based on maintaining signal integrity...if you don't mind some loss here and there, longer distances can be pushed.

[Ruler2]

http://cgi.ebay.com/25FT-DVI-D-DUAL-LINK-DIGITAL-VIDEO-CABLE-M-M-GOLD-25_W0QQitemZ200433244637QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item2eaac099dd <That should float your boat!   Although I don't know if using dual link over single link gives you any performance boost or not, it IS a good deal.

[Kermit de frog]

DVI can eliminate the "Digital to Analog to Digital" conversion process which eliminates noise and data "color" loss.
DVI also has better transmission standards when compared to VGA transmission standards.

Also, I though USB, PCIe and SATA all used digital transmissions using differential signaling and NRZ with 8b/10b encoding.  I did not know it also used analog in the final stage transmissions. 

[Skuzzy]

NRZ is just the data encoding method.  The USB, SATA and PCE-E buses are serial buses carrying digital data.  The very nature of a serial bus has its basis in the analog world.

[Kermit de frog]

My mistake, I was viewing NRZ as a type of signaling, rather than a higher level of encoding.   


I've always wondered if the "quad pumped" CPU bus used analog modulation to achieve more bits sent per cycle.  This true?

[denniswilha]

I use the matrox triple head2go system, i tried using DVI single on all three monitors, it would not produce any high resolutions, checking specs with matrox it required DVI dual, so i invested in 4 of them 1 to each monitor and 1 to the pc from matrox unit, made a world of difference, it supports all the higher resolutions. i know they make VGA units but have no idea what resolutin they will support. Dvi in my opinion is by far better in quality, and performance, as far as price VGA is cheapest, you get what you pay for.