MacBook Intel GMA950 w/ Dell 2407WFP - resolution problem

[Joseph Alten]

Hello.

I've installed Linux on my MacBook, and I'm having some issues  
getting Xorg (version 7.2 I think) to display correctly on my Dell  
2407WFP monitor. Here are the technical specs of the monitor:

Horizontal Scan Frequency kHz
30 kHz to 81 kHz (automatic)

Vertical Scan Frequency Frequency kHz
56 Hz to 76 Hz (automatic) ), exception 1920 x 1200 at 60 Hz only

Optimal Resolution
1920 x 1200 at 60 Hz

Preset Display Modes

  * VESA, 720 x 400 - 31.5 kHz Horizontal, 70.0 Hz Vertical, 28.3 MHz
  * VESA, 640 x 480 - 31.5 kHz Horizontal, 59.9 Hz Vertical, 25.2 MHz
  * VESA, 640 x 480 - 37.5 kHz Horizontal, 75.0 Hz Vertical, 31.5 MHz
  * VESA, 800 x 600 - 37.9 kHz Horizontal, 60.3 Hz Vertical, 40.0 MHz
  * VESA, 800 x 600 - 46.9 kHz Horizontal, 75.0 Hz Vertical, 49.5 MHz
  * VESA, 1024 x 768 - 48.4 kHz Horizontal, 60.0 Hz Vertical, 65.0 MHz
  * VESA, 1024 x 768 - 60.0 kHz Horizontal, 75.0 Hz Vertical, 78.8 MHz
  * VESA, 1152 x 864 - 67.5 kHz Horizontal, 75.0 Hz Vertical, 108 MHz
  * VESA, 1280 x 1024 - 64.0 kHz Horizontal, 60.0 Hz Vertical, 108 MHz
  * VESA, 1280 x 1024 - 80.0 kHz Horizontal, 75.0 Hz Vertical, 135 MHz
  * VESA, 1600 x 1200 - 75.0 kHz Horizontal, 60.0 Hz Vertical, 162 MHz
  * VESA, 1920 x 1200 - 74.0 kHz Horizontal, 60.0 Hz Vertical, 154 MHz

And here's what xrandr shows when the monitor is plugged in:

TMDS-1 connected 1152x864+0+0 (normal left inverted right) 0mm x 0mm
     1920x1200      60.0 +
     1600x1200      59.9
     1680x1050      60.0
     1280x1024      75.0     59.9
     1152x864       74.8*
     1024x768       75.1     60.0
     800x600        75.0     60.3
     640x480        75.0     60.0     59.9
     720x400        70.1

Using xrandr, I can set the display resolution of the monitor from  
pretty much anywhere around 720x400 to 1680x1050. But I can't get any  
higher than that; when I try to set it to either 1600x1200 or  
1920x1200 my monitor goes blank, and then I get a message that reads  
the following:

"Out of range signal.
Cannot display this video mode,
change computer display input to 1920x1200 @ 60Hz"

I've tried using the cvt tool to generate a reduced-blanking modeline  
and then using it with xrandr, but it doesn't help. I've also tried  
using Colas XFree Modeline Generator, but when I enter the range  
values according to the technical specifications of the monitor, the  
generator says that my resolution is too low.

By the way, there is nothing wrong with my hardware, as Windows and  
Mac OS X currently exist on my hard drive as part of a triple-boot  
setup, and they have no issues whatsoever with using this monitor at  
its native resolution. Another thing worth noting is that I'm  
connecting to this thing via DVI; I had another machine that I tried  
connecting to this thing using VGA, and all I did was set the  
resolution in the xorg.conf file and it worked perfectly...

Thanks in advance,

Joe