Re: Video card and LCD displays
- From: "GuessWho" <me@xxxxxxxxxxx>
- Date: Fri, 28 Jul 2006 13:44:41 GMT
"Paul" <nospam@xxxxxxxxxx> wrote in message
news:nospam-2707062337440001@xxxxxxxxxxxxxxxx
In article <m28yg.11278$1Z5.3135@xxxxxxxxxxxxxxxxxxxx>, "GuessWho"
<me@xxxxxxxxxxx> wrote:
I have a 19" Sony CRT and a nVidia MX series video board on this =
machine. According to my Control Panel/Display, I can get 1600 x 1200 =
resolution.
I've been thinking of getting a bigger LCD monitor but according to the =
nVidia site:
Integrated Dual-Channel TMDS
Transmitters - enabling two independent
Digital Flat Panels (DFP) displays at
resolutions up to 1280x1024.
The site also indicates different supported resolutions for CRT and LCD =
monitors.
Does this mean that I need a different video card if I want to use the =
greater resolution of the 20" or greater LCD monitors?
For routine computer work i.e. email and other web viewing, image =
editing, TV/DVD viewing, office related tasks but no gaming, is a 4:3 or
=
16:9 display preferred?
TIA,
Wayne
According to this page, a single DVI link has a capacity to handle
2.6 megapixels (H x V) at a refresh rate of 60Hz.
http://www.tech-faq.com/dvi.shtml
This page gives a formula for the necessary pixel clock rate, and
they include a 5% and 10% factors for blanking period. Blanking
period is essential for a CRT, as the beam has to retrace back to the
top and left of the screen during vertical and horizontal retrace.
An LCD doesn't have retrace, being all digital, so the blanking
intervals (periods of inactivity) can be reduced.
http://www.ecinemasys.com/technotes/files/AN010%20-%20DVI%20Interconnect%20Limitations.pdf
The spec calls for operation at 165MHz for the pixel clock. Some
early GPUs weren't compliant with the spec, and those cards cannot
give a good quality output when running that fast.
When a lower resolution is listed, it can mean one of two things.
It can imply a high refresh rate. If the spec says 1280x1024 and
the manufacturer assumes 85Hz or 100Hz refresh rate, then that burns
up some of the link capacity. If the link is only good for 135MHz
pixel clock and not the full 165MHz, that would be another reason.
The analog output is the other output type on your video card.
The analog VGA output is constrained by the DAC used in the GPU. The
standard number these days is 400MHz, which apparently is good
for 2048x1536 @ 85Hz. I don't have a formula handy for converting
between the two sets of numbers. At high resolutions, on the
analog outputs, the problem would be cable quality - reflections
from poorly matched/terminated cables, is what messes up the
appearance of analog output.
I looked at monitors up to 23" on Newegg, and 1920 x 1200 @ 56 - 85Hz
is their resolution. That should be in range of a modern video card
with a single-link DVI connector (and perhaps reduced blanking
interval). But if the digital output on your current video card
is not good enough to make it to 165MHz, you might want to
test and see how it goes. If you see snow on the screen or other
artifacts from the digital output of your MX series card, you
should be able to pick up another cheap low end card which has
a better quality DVI output. There are still AGP cards around.
Paul
Thanx Mike and Paul
Although I don't understand the info in the links provided by Paul, you both
seem to be saying the same thing. Namely that my current video card will
support 1600 x 1200 LCD panels over DVI.
Paul, I have considered a higher end video card, but I'm not sure if I want
to stick with my current 939 AGP mobo.
Wayne
.
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