Centos 6.5. Setting display resolution.

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YKdev
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Joined: 2014/04/29 18:26:44

Centos 6.5. Setting display resolution.

Post by YKdev » 2014/04/29 19:23:50

Hi.
I have CentOS 6.5 installed on my machine. I recently have installed the nVidia GT 9600 proprietary driver. And since then I have only 2 display resolution options in the System Preferences->Display. The monitor is Samsung SyncMaster E1920. I need it to work in 1280x1024 60 Hz mode. I tried different recipes found on the web, but still I can't manage it.
What is the correct way to set the resolution settings for the display in CentOS 6.5?
Thanks to everyone in advance.

YKdev
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Joined: 2014/04/29 18:26:44

Re: Centos 6.5. Setting display resolution.

Post by YKdev » 2014/05/05 07:12:07

Any idea??? Advice?

YKdev
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Re: Centos 6.5. Setting display resolution.

Post by YKdev » 2014/05/05 10:16:27

When I try to edit the xorg.conf configuration file (/etc/X11/) nothing changes. There's no effect when I restart the X-session or reboot.
And one more detail, I connect the monitor via VGA switch. /var/log/Xorg.0.log contains the following strings:
No modes were requested; the default mode "nvidia-auto-select" will be used as the requested mode.
and
Unable to get display device CRT-0's EDID; cannot compute DPI

gerald_clark
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Re: Centos 6.5. Setting display resolution.

Post by gerald_clark » 2014/05/05 12:53:12

Try connecting the monitor directly. You may need a better switch.

YKdev
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Re: Centos 6.5. Setting display resolution.

Post by YKdev » 2014/05/05 18:09:54

When connected directly the monitor autodetected and everything works fine with optimal resolution. But I can't use it without KVM-switch and I can't change the switch. I googled. I suppose the problem is that the nvidia driver can't read EDID. But I wonder why changes in xorg.conf doesn't take effect anyway. How can I overcome the problem? Waht documentation to read for more information?

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TrevorH
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Re: Centos 6.5. Setting display resolution.

Post by TrevorH » 2014/05/05 18:15:55

More likely you have a switch that doesn't pass EDID information which is why it doesn't work. You could try a different cable but really I suspect the KVM is rubbish. Is it a mechanical one or an electronic switch? Mechanical ones are almost always rubbish...
CentOS 6 will die in November 2020 - migrate sooner rather than later!
Info for USB installs on http://wiki.centos.org/HowTos/InstallFromUSBkey
CentOS 5 is dead, do not use it.
Full time Geek, part time moderator. Use the FAQ Luke

YKdev
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Re: Centos 6.5. Setting display resolution.

Post by YKdev » 2014/05/05 19:28:33

I'm not sure if it's mecanical or electronic. Chances are it's electronic because switching can be made by double hitting the NumLock key on the keyboard. And there is no toggle switch on it. Olny buttons. Up to 4 comps may be connected. Not sure about exact model. I'm not in place right now.
I think that some of the VGA pins are used for keyboard and mouse.
Now how can I manually set the resolution and other parameters? Without the EDID.

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jlehtone
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Re: Centos 6.5. Setting display resolution.

Post by jlehtone » 2014/05/06 12:54:26

What have you set in the xorg.conf? Nvidia driver has options to ignore the EDID. Some are probably required.

YKdev
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Re: Centos 6.5. Setting display resolution.

Post by YKdev » 2014/05/06 17:45:25

I was trying to edit the Screen section by adding Modeline string to the Display subsection. And I've tried to edit the Monitor section. To no avail.
I resolved the issue another way. Using the Phoenix EDID Designer tool (Windows application) I exported the EDID data to the file and then I added the following string to the Device section:
Option "CustomEDID" "VGA-0:/etc/X11/custon_EDID.raw"
(Here's the link http://ubuntuforums.org/showthread.php?t=316985)

After that when I reboot the system the monitor shows message about "Not really the best resolution. 1280x1024 is recommended" or so. I went to the NVidia driver setting (System -> Preferences -> NVIDIA X Server Setting) under the root, set the resolution 1280x1024 and clicked Save to X Configuration file. Now it is quiet about "not the best resolution option".
But I'm not fully satisfied.
May somebody advice me a good documentation? (X Server, xorg.conf syntax and so on)

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jlehtone
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Re: Centos 6.5. Setting display resolution.

Post by jlehtone » 2014/05/07 12:58:15

Nvidia driver from ElRepo contains /usr/share/doc/nvidia-x11-drv-*/xconfigoptions.html

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