今天继续解决这个问题，详细研究了xconfig以后生成的xorg.conf文件， 把HorizSync和VertRefresh数值调低 ，把monitor和Device的ModelName手动填上，我的是BenQ FP71G+和nVidia Corporation G70 [GeForce 7600 GS]，Google一下找到一个Screen的配置文件，先不管了全部copy过来，重启，OK了。
附xorg.conf文件完整配置，如果有人跟我同样的状况可以完全copy后把ModelName改成自己的应该就可以了。
引用:# nvidia-xconfig: X configuration file generated by nvidia-xconfig
# nvidia-xconfig: version 1.0 (buildmeister@builder3) Wed Sep 12 14:29:35 PDT 2007
Section "ServerLayout"
Identifier "Layout0"
Screen 0 " Screen0"0 0
InputDevice "Keyboard0" "CoreKeyboard"
InputDevice "Mouse0" "CorePointer"
EndSection
Section "Files"
RgbPath "/usr/X11R6/lib/X11/rgb"
ModulePath "/usr/lib/xorg/modules"
EndSection
Section "Module"
Load "dbe"
Load "extmod"
Load "type1"
Load "freetype"
Load "glx"
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"
Identifier "Monitor0"
VendorName "BNQ"
ModelName "BenQ FP71G+"
HorizSync 31.0 - 83.0
VertRefresh 56.0 - 76.0
Option "DPMS"
EndSection
Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "nVidia Corporation G70 [GeForce 7600 GS]"
BusID "PCI:1:0:0"
EndSection
Section "Screen"
Identifier " Screen0"
Device "Device0"
Monitor "Monitor0"
SubSection "Display"
Viewport 0 0
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 4
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 8
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 15
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 16
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 24
EndSubSection
EndSection