Archived from groups: alt.comp.periphs.videocards.ati (
More info?)
I've never seen a case where, when the DVI port worked (at the correct
native resolution of the display), the DVI image was inferior to the
analog image. I do agree with your second statment that sometimes the
difference is noticeable and sometimes it's not.
As to cases in which the DVI port doesn't seem to work (either "at all"
or at the native resolution of the panel), those are usually caused by
either the wrong cable type (using a single-link cable when a dual-link
cable is required) or by incompatability between the LCD monitor's
firmware and the firmware and/or drivers for the video card.
DVI devices have a "DDC" (data display channel) which is a 2-way serial
port over which the monitor and video card "talk" to each other about
what resolutions and refresh rates are supported, etc.
Although it's become a lot less common, there have been firmware
incompatabilities between some DVI LCD monitors and some video cards
(either the firmware or the drivers) in which this exchange could not
properly take place. Some video card drivers (including quite a few ATI
drivers) will not allow manual override of this "feature", leaving you
"stuck" at the wrong resolution or refresh rate (often 640x480x16, but
sometimes a higher, but still wrong, configuration).
J. Clarke wrote:
> Barry Watzman wrote:
>
>
>>The image quality is better with DVI.
>
>
> Not always. For example I have a Matrox board that cannot drive a current
> generation LCD at its design resolution from the DVI port.
>
> Sometimes there is a noticeable difference between DVI and analog at the
> design resolution, sometimes not.
>
>