# dvi flicker [solved]

## dreamerme

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 when you use a cellphone near a CRT monitor.  There is no flicker using Analog, and all lower resolutions are ok using DVI.  This problem occurs under Windows as well.

After some googling, I found out that under Windows, I can use the nvidia control panel to set "CVT reduced blanking".  This solves the problem under Windows.  My nvidia control panel looks like this:  http://www.comp.nus.edu.sg/~leeweiqi/customtimings.jpg

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 of

```
  

# 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

```

But still no luck.

Any ideas?Last edited by dreamerme on Tue Aug 07, 2007 3:50 pm; edited 1 time in total

----------

## NeddySeagoon

dreamerme,

The modeline is the right approach but the nvidia driver will ignore it unless you also add some nvidia specific options to your Device section too.

I forget exactly what they are and they have changed from time to time too. Look in  /usr/share/doc/nvidia-drivers-1.0.9639/README.bz2  (put your version number in there). Its a big file, you want Appendix D. X Config Options.  Start reading here 

```
Option "UseEdidFreqs" "boolean"
```

Thats from my 9639 version ... yours may differ.

----------

## dreamerme

thanks, got it fixed.  Added these to xorg.conf:

```

Option      "ExactModeTimingsDVI"  "true"

Modeline "1600x1200_cvtrb"  130.25  1600 1648 1680 1760  1200 1203 1207 1235  +HSync -Vsync

```

----------

