VGA 2nd Monitor on ATI X1650 - refresh rate?

[DonWaugaman]

I have an ATI X1650 video card, attached to two monitors. The secondary monitor is a Hitachi CM751 CRT, which previous versions of Fedora have driven at a 75Hz refresh rate at the maximum 1600x1200 resolution.

After installing the Fedora 15 Beta on this computer, the Plymouth boot screen comes up with a 75Hz refresh rate. Once the login screen shows, however, the monitor gets shifted back to a 60Hz refresh rate, and stays there through several screen flickers (looking at the Xorg.0.log file, it appears these are due to EDID probes). The DDC-gathered modelines in the file include the VESA-standard 1600x1200@75Hz modeline, so I'm at a bit of a loss as to why that mode is not selected when I ask for the 1600x1200 resolution in the display settings tool.

Anyone have any ideas for how to get this mode to work? 60Hz really strains my eyes after a while, so it's pretty hard to work with it this way.

The LCD on the other head, I should add, has a max refresh rate of 60Hz in the same 1600x1200 mode, so I'm worried that somehow that setting is getting used for the CRT. But again, as I said, previous versions of Fedora have done fine with this setup, so I'm sure there's some way to make it work.

I've attached my Xorg.0.log in case this would help.

Thanks in advance,

Don

[DonWaugaman]

Well, I got a little farther on this.

I used xrandr to set my CRT monitor into a 75Hz refresh rate mode. However, this setting didn't carry over between reboots, or even logging out and back in, so I continued to hunt for a better solution.

Using the instructions at <a href="http://wiki.debian.org/XStrikeForce/HowToRandR12"http://wiki.debian.org/XStrikeForce/HowToRandR12</a>, I added a section to my xorg.conf:

# xorg.conf to allow for use use of the Hitachi CM751 at max refresh rate

Section "Monitor"
Identifier "CRT Monitor"
Option "RightOf" "LCD Monitor"
DisplaySize 360 270
Modeline "1600x1200@75Hz" 202.50 1600 1664 1856 2160 1200 1201 1204 1250 +hsync +vsync
Option "PreferredMode" "1600x1200@75Hz"
EndSection

Section "Device"
Identifier "ATI X1650"
Option "Monitor-VGA-0" "LCD Monitor"
Option "Monitor-DVI-0" "CRT Monitor"
EndSection

(It's a little confusing because I put the CRT on the DVI output, and the LCD on the VGA output - both are driven by VGA, the LCD is shared with another computer that uses its DVI port. But anyway...)

So I try booting with this setup. Plymouth comes up with a 75Hz refresh rate, as does GDM - so I figure I'm home free. But, when I log in to the system, the CRT gets shifted back down to a 60Hz refresh rate!

xrandr -q output looks like this:
[dpw@chwesley ~]$ xrandr -q
Screen 0: minimum 320 x 200, current 3200 x 1200, maximum 8192 x 8192
VGA-0 connected 1600x1200+0+0 (normal left inverted right x axis y axis) 408mm x 306mm
1600x1200 60.0*+ 75.0
1280x1024 75.0 60.0
1280x960 60.0
1152x864 75.0
1024x768 85.0 75.1 70.1 60.0
832x624 74.6
800x600 85.1 72.2 75.0 60.3 56.2
640x480 85.0 72.8 75.0 66.7 60.0
720x400 70.1
S-video disconnected (normal left inverted right x axis y axis)
DVI-0 connected 1600x1200+1600+0 (normal left inverted right x axis y axis) 360mm x 270mm
1600x1200@75Hz 75.0 +
1600x1200 75.0 70.0 60.0*
1280x1024 85.0 75.0
1152x864 75.0
1024x768 85.0 75.1 70.1 60.0
832x624 74.6
800x600 85.1 72.2 75.0 60.3 56.2
640x480 72.8 75.0 66.7 60.0
720x400 87.8 70.1

As you can see, the modeline that I put in the xorg.conf is the preferred mode, but for some reason, the X server doesn't select it when I logged in, preferring to use the poorer refresh rate of the other mode. So I'd have to use xrandr again whenever I log in, which is a less than perfect solution.

This is about as close as I can get to just what I want, but it's still maddeningly far away. Any one else have any ideas?

Thanks,

Don