I'm using an LG L2000C 20" LCD and an MSI 7300GT graphics card, with nvidia drivers 100.14.11. I have a problem with flickering which occurs only when I use DVI output and set the resolution to 1600x1200. The flicker effect is similar to the type of flicker you get when you use a cellphone near a CRT monitor. There is no flicker using Analog, and all resolutions lower than 1600x1200 are ok using DVI. This problem occurs under Windows XP as well.
After some googling, I found out that under Windows XP, I can use the nvidia control panel to set "CVT reduced blanking". This solves the problem under Windows.
So I tried to modify the timings under linux, first by setting
Option "ExactModeTimingsDVI" "true"
in xorg.conf, then based on the nvidia CP settings, I tried using this modeline:
Modeline "1600x1200_60" 130.0025 1600 1648 1680 1760 1200 1203 1207 1235 -HSync +Vsync
But the flickering is still there.
I also tried using the CVT calculator, which gives a modeline
# 1600x1200 @ 60.00 Hz Reduced Blank (CVT)
# field rate 59.92 Hz; hsync: 74.01 kHz; pclk: 130.25 MHz
Modeline "1600x1200_60.00_rb" 130.25 1600 1648 1680 1760 1200 1203 1207 1235 +HSync -Vsync
I have tried using pci=nommconf and idle=poll kernel parameters too.
But still no luck.