Archived from groups: alt.comp.periphs.mainboard.asus (
More info?)
In article <nospam-2605041634180001@192.168.1.177>, nospam@needed.com
(Paul) wrote:
> In article <2hk3csFdbnrbU1@uni-berlin.de>, Roy Coorne
> <rcoorne@hotmail.com> wrote:
>
> > Bubba Yarfkowitz wrote:
> > ...
> >
> > > and I'd like to find a solid video card with digital output that I can
> > > use. I'm not a gamer so I don't believe 3D is a big priority. Most of
> > > my priorities center around graphic and video editing, and standard apps
> > > like the Office suite. And the Freecell games I seem to play
> > > incessantly.
> >
> > I would consider a Matrox G550 or - more expensive - a Matrox P650 or
> > - cheaper - a Radeon 9xxx (by Asus, Sapphire or...).
> >
> > Roy
>
> I've seen one post in this group, from people who aren't completely
> happy with their DVI experiences.
>
> Note in this post, the mention of _potential_ problems above 1280x1024
> resolution.
>
>
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&selm=sOGcnXzJFqqnoQ2jXTWcow%40speakeasy.net
>
> Since your panel is 1600x1200, you'd probably want to run it in its
> native resolution, and bump up the font size in Windows. This way,
> there is no resampling aliasing inside the monitor to spoil the
> display when run at slightly lower resolutions.
>
> This page hints at a 1280x1024 limit with a single TDMS link at
> 165MHz. As a result, the video card should have a dual TDMS link
> on the DVI connector - I think that is how you get enough bandwidth
> for displays larger than that.
>
>
http://www.pacificcable.com/DVI_Tutorial.htm
>
> Now, the tough part is finding a review of a video card, that
> actually evaluates the card in enough detail to know whether it
> has dual link or not.
>
> Don't take my word as gospel, but do try asking a few questions
> of both the panel vendor (does it have dual link at its end and
> what video card do you recommend) and the video card maker (does
> it have dual TDMS links on the DVI connector). No sense buying
> any old video card and finding that you can only use the analog
> output.
>
> Page 52 of this manual for the G450, shows what looks like a full
> two TDMS links. TDMS data 0,1,2 is one link worth of data and
> TDMS data 3,4,5 is the other link.
>
>
http://www.matrox.com/mga/support/user_manuals/mill_g450/millg450_en.pdf
>
> The problem will be getting that kind of detail for more current
> video cards.
>
> I just looked at the back of my ATI branded 9800Pro and it seems
> to have the full DVI-I connector.
>
> HTH,
> Paul
I was rereading this post, and dug out a calculator, and the numbers
don't make sense. In fact, on the DVI connector, there is an
up to 165MHz clock, but the data on a differential pair of pins
runs at 10x that rate, and the coding is 80% efficient, so a full
8 bits are delivered per clock. There is enough bandwidth for more
than 1280x1024 - it really depends on the refresh rate selected.
Now, I thought that LCD monitors only update the screen at a 60Hz
rate, even when the refresh on the computer is set at up to 75Hz.
Not really sure about that.
There is a nice picture of the DVI sending data in this article
and compares DVI to another interface type. This is to show
the sending of 10 bits per clock cycle, and the fact that only
eight bits are used for the purposes of updating the screen:
http://www.national.com/nationaledge/may01/lvds.html
http://www.national.com/nationaledge/may01/images/lvds_3(big).gif
Page 6 of this document, shows what resolutions and refresh rates
are possible with single and dual TDMS links.
http://www.proxima.com/downloads/pdf/DVI-WhitePaper.pdf
Display Single-Link DVI Dual-Link DVI
60-Hz LCD with 1920x1080 HDTV 2048x1536 QXGA
5% blanking Interval
75-Hz CRT with approx 1280x1024 SXGA 2048x1536 QXGA
15% blanking interval
85-Hz CRT with approx 1280x1024 SXGA 1920x1080 HDTV
15% blanking interval
If you stay at 60-Hz refresh, I think 1920x1080 has roughly
the same number of bits as 1600x1200, so a single TDMS link
should be able to do it, assuming the cable is good quality.
Sending a signal at 1650Mb/sec is roughly the same as sending
signals to a SATA drive, and you cannot put a very long cable
on SATA. Maybe the reason some people have problems, is the
silicon on the video card is not capable of producing a clean
signal at 1650Mb/sec. That is reasonably challenging for
silicon (but is easy with Si-Ge).
HTH,
Paul
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