sounds like you have similar monitor to me, i have 19" 930BS from samsung, which has same resolution.
im on SUSE, and the control panel could read the monitor details from the vendor driver cd that comes with the monitor, this generates following settings in xorg.conf:
Code:
Section "Monitor"
DisplaySize 386 290
HorizSync 31-81
Identifier "Monitor[0]"
ModelName "SYNCMASTER 930B/930BC/930BF(DIGITAL)"
VendorName "SAMSUNG"
VertRefresh 62-75
UseModes "Modes[0]"
EndSection
Section "Modes"
Identifier "Modes[0]"
Modeline "1280x1024" 134.72 1280 1368 1504 1728 1024 1025 1028 1068
Modeline "1280x1024" 114.54 1280 1360 1496 1712 1024 1025 1028 1062
Modeline "1280x960" 126.27 1280 1368 1504 1728 960 961 964 1001
Modeline "1280x960" 107.32 1280 1360 1496 1712 960 961 964 995
Modeline "1280x800" 104.35 1280 1360 1496 1712 800 801 804 835
Modeline "1280x800" 88.68 1280 1352 1488 1696 800 801 804 830
Modeline "1152x864" 102.08 1152 1224 1352 1552 864 865 868 901
Modeline "1152x864" 86.70 1152 1224 1344 1536 864 865 868 896
Modeline "1280x768" 99.17 1280 1352 1488 1696 768 769 772 801
Modeline "1280x768" 84.35 1280 1344 1480 1680 768 769 772 797
Modeline "1024x768" 79.52 1024 1080 1192 1360 768 769 772 801
Modeline "1024x768" 67.48 1024 1080 1184 1344 768 769 772 797
Modeline "800x600" 47.53 800 840 920 1040 600 601 604 626
Modeline "800x600" 40.19 800 832 912 1024 600 601 604 623
Modeline "768x576" 43.52 768 800 880 992 576 577 580 601
Modeline "768x576" 37.37 768 800 880 992 576 577 580 598
Modeline "640x480" 29.84 640 664 728 816 480 481 484 501
Modeline "640x480" 25.10 640 656 720 800 480 481 484 498
EndSection
Section "Screen"
DefaultDepth 24
SubSection "Display"
Depth 15
Modes "1280x1024" "1280x960" "1280x800" "1152x864" "1280x768" "1024x768" "800x600" "768x576" "640x480"
EndSubSection
SubSection "Display"
Depth 16
Modes "1280x1024" "1280x960" "1280x800" "1152x864" "1280x768" "1024x768" "800x600" "768x576" "640x480"
EndSubSection
SubSection "Display"
Depth 24
Modes "1280x1024" "1280x960" "1280x800" "1152x864" "1280x768" "1024x768" "800x600" "768x576" "640x480"
EndSubSection
SubSection "Display"
Depth 32
Modes "1280x1024" "1280x960" "1280x800" "1152x864" "1280x768" "1024x768" "800x600" "768x576" "640x480"
EndSubSection
SubSection "Display"
Depth 8
Modes "1280x1024" "1280x960" "1280x800" "1152x864" "1280x768" "1024x768" "800x600" "768x576" "640x480"
EndSubSection
Device "Device[0]"
Identifier "Screen[0]"
Monitor "Monitor[0]"
EndSection
Section "Device"
BoardName "RV280 5960"
BusID "1:0:0"
Driver "radeon"
Identifier "Device[0]"
Screen 0
VendorName "ATI"
EndSection
You could probably put the 1280x1024 lines in your config file and restart x.
Note that this drives it at 60hz not 75hz, i've not figured out how to do 75hz, but the manual says 60hz is optimum mode.