For those who are interested in this:
Typically your x configuration (xorg.conf) will have something in that looks pretty much like this:
Section "Device"
Identifier "NVIDIA Corporation NV43 [GeForce 6600]"
Driver "nv"
BusID "PCI:4:0:0"
Option "TwinView" "False"
Option "TwinViewOrientation" "RightOf"
Option "UseEdidFreqs" "False"
Option "SecondMonitorHorizSync" "UseEdidFreqs"
Option "SecondMonitorVertRefresh" "UseEdidFreqs"
Option "MetaModes" "1280x1024,1280x1024; 1024x768,1024x768"
Option "UseDisplayDevice" "CRT"
Option "ConnectedMonitor" "CRT, CRT"
EndSection
just update it to look like this:
Section "Device"
Identifier "NVIDIA Corporation NV43 [GeForce 6600]"
Driver "nv"
BusID "PCI:4:0:0"
Option "TwinView" "True"
Option "TwinViewOrientation" "RightOf"
Option "UseEdidFreqs" "True"
Option "MetaModes" "1280x1024,1280x1024; 1024x768,1024x768"
Option "SecondMonitorHorizSync" "28.0-51.0"
Option "SecondMonitorVertRefresh" "43.0-60.0"
Option "UseDisplayDevice" "CRT"
Option "ConnectedMonitor" "CRT, CRT"
EndSection
I have not fully tested this, but do not think that it will cause any trouble...