Samsung SyncMaster 720N working only @60Hz

Laszlo Kustan lkustan at
Tue Apr 8 03:42:12 PDT 2008

I have Suse 10.3 installed on my comp with NVidia GeForce 6100 nForce 430
graphics card.
Unfortunately I have problems setting my monitor (Samsung SyncMaster 720N)
to the desired refresh rate (1280x1024 at 75Hz).
I have read the mailing list archive, I could see this problem at several
Samsung monitors but couldn't see any solution (if there is a solution in
the archive, sorry, I was not enough attentive).

This model isn't in the list of monitors,  I tried to set the horizontal and
vertical refresh ranges according to the monitor's manual:
Horizontal 30 ~ 81 kHz
Vertical 56 ~ 75 Hz
Optimum resolution 1280 x 1024 at 60 Hz
Maximum resolution 1280 x 1024 at 75 Hz
Maximum Pixel Clock
140 MHz

I tried to generate modeline with the proper settings, but the generator
gives me only bad data (pixel clock too big)
This is the vesa preset from the manual:
VESA, 1280 x 1024 79.976 75.025 135.00 +/+
this is the modeline I tried:
Modeline "1280x1024" 135.00 1280 1296 1440 1688 1024 1025 1028 1066 +HSync
but it does not work.

The resolution switcher applet let's me select between 60 Hz and 75 Hz
although I have one single modeline in xorg.conf. If I select 75 Hz, it
configures only 69 Hz and after restart I stil have 60 Hz.

I tried with other distros as well, same behaviour, it is clearly an xorg
In Windows it works normally... I can sense the difference between the linux
and windows settings, my eyes hurt after 1-2 hours in linux, in windows no
such problems.

Please give me some solution to this problem.
Thanks, Laszlo Kustan
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