DVI video cards

[Al Pollock]

Hello people, I see ATI has video cards with DVI ? Digital video in ? I also see some lcd monitors have the same white connector dvi .some of the lcds monitors have the dvi connector some don't .............Please tell all not quite sure about DVI as marked on video cards
Thanks all

AL

[doctorgonzo]

Video signals start out as digital data: 16-, 24-, or 32-bit numbers that determine the color of a particular pixel. Older CRT monitors, however, required analog inputs (just like TVs are analog). The blue VGA d-sub connector on monitors and video cards is analog.

Then LCD panels came along. LCD panels also use digital signals for displaying images, unlike analog monitors. However, since most video cards just put out analog signals when LCD monitors first started appearing in the market, LCD monitors also used the blue VGA d-sub connector. Thus, the signal went from digital (video card) to analog (cable) to digital (LCD monitor).

People soon figured out that cutting out the middle analog step would make signal quality better, since there would be no conversions. Thus, the DVI connector was born. It is simply the digital version of analog monitor connections. Less expensive video cards and LCD monitors tend to have just the blue VGA d-sub connector, not the DVI connector.

[thefultonhow]

Originally Posted by Al Pollock DVI ? Digital video in ?

Digital Video Interface. As Doctorgonzo said, it's basically a way to connect displays with a straight digital-to-digital connection. It's actually a video-out port when it's on a video card, just like VGA is.

[Al Pollock]

So are you guys saying if a LCD monitor has a standard d plue plug and no white digital plug its not a dvi monitor ? all the nec lcd monitors I see have no white dvi plug , yet I see samsung has the dvi white plug and I see the cable is extra????

confused in PA

AL

[RJ]

So are you guys saying if a LCD monitor has a standard d plue plug and no white digital plug its not a dvi monitor ?

Correct. These are the cheap stuff I'd stay away from. They are not capable of displaying the best picture they can.

all the nec lcd monitors I see have no white dvi plug , yet I see samsung has the dvi white plug and I see the cable is extra????

Nearly every manufacturer has models with DVI available. The cable should be included, but I believe sometimes you do have to buy it extra. They aren't expensive, though.

I see ATI has video cards with DVI ?

Umm. . . every video card, no matter whether they are ATI or nVidia, has the DVI port (except the very very cheap ones). It's been standard for years

RJ

[Al Pollock]

I see a 17" view sonic with dvi any comments???

AL

[Al Pollock]

I also see some with a d blue internally connected cable and the white plug also??? Does this mean they can be run analog or digital

AL

Really confused

[thefultonhow]

Originally Posted by Al Pollock I also see some with a d blue internally connected cable and the white plug also??? Does this mean they can be run analog or digital

Basically all DVI-compatible monitors can also be run off VGA. (Apple's Cinema Displays are the notable exception.)

[piasabird]

The DVI connector does not guarantee a Digital only device. The DVI connector is designed to have the capability to be both Digital and Analog, it just depends on the implementation. Are monitors actually digital or is the signal digital and then converted to analog?

How do you know for sure?

Are all monitors actually Analog?

Prove it!

The plug means nothing.

I am really just curious about this subject. However, an article on the topic may be of interest to me.

[thefultonhow]

Originally Posted by piasabird Are monitors actually digital or is the signal digital and then converted to analog? Are all monitors actually Analog?

No, LCDs are inherently digital. Any given pixel is always on (1) or off (0), and electrically so. In contrast, CRTs utilize an electron gun to turn their phosphors "on" or "off" -- they are sent analog data for vertical and horizontal coordinates. So CRTs are analog and LCDs are digital.

Hence, the traditional video card will convert the digital data going through the card to analog waves via what's called a RAMDAC. When a CRT receives the resultant waves, it can use them right away to draw the picture, but an LCD has to convert them back to digital before they can be used. In the two conversion processes (digital-to-analog and analog-to-digital), data is lost and interference is introduced, thus degrading the picture quality on the analog-connected LCD.

That's why DVI was invented. DVI by nature is a fully digital connection. This way there is no data conversion and thus no data loss. Therefore the picture quality is, essentially, perfect. DVI does not use a RAMDAC -- it uses another chip that I forget the name of to convert digital data to a digital DVI signal.

Yes, the connector on the video card also puts out analog data so that a DVI-to-VGA adaptor can be used to run a CRT (although on older video cards with DVI connectors that did not support dual-head, this was not the case -- I've seen a GeForce2 card that had a digital-only DVI connector that could be used instead of the analog VGA connector). However, the cable that carries the DVI signal does not carry an analog signal too. I've seen an IBM CRT that uses a DVI cable -- but it has circuitry inside it that does the digital-to-analog conversion.

Originally Posted by piasabird The plug means nothing.

Not true. If a monitor has a DVI plug, it is guaranteed to have a fully digital signal path. DVI monitors also have an analog VGA plug for computers that don't have a DVI connector -- and they have an analog-to-digital converter for that plug. So picture quality is not as good on that plug as it is on the DVI one. I have seen this firsthand on my Dell 2001FP -- my computer is connected via DVI, but I connect computers that I'm working on via VGA. Even with both computers at native resolution (1600x1200), the VGA connection is much blurrier than the DVI one.

[Al Pollock]

I am still not clear on all of this.........I have seen a samsung with a video cable and at the end Is a blue analog plug but there is also a white socket on the monitor to plug in a digital cable

[thefultonhow]

Originally Posted by Al Pollock I am still not clear on all of this.........I have seen a samsung with a video cable and at the end Is a blue analog plug but there is also a white socket on the monitor to plug in a digital cable

Yeah, it supports both digital and analog connections. I'm not sure if it comes with the DVI cable, but you would just use that instead of the VGA cable if your computer supports DVI.