É uma correção suja, mas funciona para mim no Ubuntu 13.10.
Na seção "Monitor" alterei VertRefresh 75.0 - 75.0 e adicionei à seção "Tela:" Opção "UseEDIDFreqs" "False"
# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings: version 331.20 (buildmeister@swio-display-x86-rhel47-05) Wed Oct 30 18:20:32 PDT 2013
Section "ServerLayout"
Identifier "Layout0"
Screen 0 "Screen0" 0 0
InputDevice "Keyboard0" "CoreKeyboard"
InputDevice "Mouse0" "CorePointer"
Option "Xinerama" "0"
EndSection
Section "Files"
EndSection
Section "InputDevice"
# generated from default
Identifier "Mouse0"
Driver "mouse"
Option "Protocol" "auto"
Option "Device" "/dev/psaux"
Option "Emulate3Buttons" "no"
Option "ZAxisMapping" "4 5"
EndSection
Section "InputDevice"
# generated from default
Identifier "Keyboard0"
Driver "kbd"
EndSection
Section "Monitor"
# HorizSync source: edid, VertRefresh source: edid
Identifier "Monitor0"
VendorName "Unknown"
ModelName "BenQ FP93GX+"
HorizSync 31.0 - 83.0
VertRefresh 75.0 - 75.0
Option "DPMS"
EndSection
Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce GTX 260"
EndSection
Section "Screen"
Identifier "Screen0"
Device "Device0"
Monitor "Monitor0"
DefaultDepth 24
Option "Stereo" "0"
Option "metamodes" "1280x1024_75+0+0"
Option "UseEDIDFreqs" "False"
Option "SLI" "Off"
Option "MultiGPU" "Off"
Option "BaseMosaic" "off"
SubSection "Display"
Depth 24
EndSubSection
EndSection