DC wrote:
On Wed, 13 Apr 2011 14:42:42 -0500, rocket777
wrote:

I had been struggling to find a way to get both my 1920x1080 LG monitors
to work correctly (they are different models, m237wd and w2353VP) on my
win xp pro 32 bit system. After much effort, I finally have it working.
Here's my story in case it helps someone else.

Snip

I'm still confused as to why using all 15 pins causes it to not work at
full monitor resolution, but now that it works, I'm done fixing it, so I
don't know if pin 9 is really the problem or a combination of pin 9 and
the monitor driver files. But there's something about that 15 pin cable
and my Radeon interface that it doesn't like.

That's weird !

This diagram has pin 9 missing:

http://pinouts.ru/Video/VGA15_pinout.shtml


When you scrolled down that web page, did you see this ?

http://pinouts.ru/Video/VGA15_pinout.shtml

"VGA DDC2 pinout details

VGA pin new function
9 Optional +5V output from graphics card
12 Bidirectional data line (SDA)
15 Data clock (SCLK)"

That explains what pin 9 would be doing, if it was
present, and the video card supported it. Pin 9 delivers
power, so the EDID can be read. And DDC2 is bidirectional,
so it is capable of more than plain EDID reading.

More info on DDC can be found here.

http://www.vesa.org/vesa-standards/standards-faq/

"DDC

Q: Why is +5 volts on pin 9 mandatory for system units and/or graphic cards.

A: It is becoming common for system management software to interrogate peripheral
devices for product type and serial number as a form of asset management. This
is usually scheduled for nighttime but if the monitor is powered off then no
data can be collected. Providing +5 volts allows the DDC circuit in the monitor
to remain active even when the monitor itself is powered off.
Ref.: Section 4.1.4.1"

HTH,
Paul