How can I alter my Xorg config file to fix the screen distortion I am experiencing?

Question

I have a system running FreeBSD 8.2-RELEASE-p2 with an LCD display attached capable of running at a native resolution of 1600 x 900. I have configured Xorg the way I think it should work, however the right side of the display image shows on the left side of the screen:

The display looks correct at lower resolutions... Is it some setting in the Xorg.conf file causing this? What steps can I try to troubleshoot / correct this?

Here is my Xorg.conf file:

Section "ServerLayout"
    Identifier     "X.org Configured"
    Screen      0  "Screen0" 0 0
    InputDevice    "Mouse0" "CorePointer"
    InputDevice    "Keyboard0" "CoreKeyboard"
    Option "AutoAddDevices" "false"
EndSection

Section "Files"
    ModulePath   "/usr/local/lib/xorg/modules"
    FontPath     "/usr/local/lib/X11/fonts/misc/"
    FontPath     "/usr/local/lib/X11/fonts/TTF/"
    FontPath     "/usr/local/lib/X11/fonts/OTF"
    FontPath     "/usr/local/lib/X11/fonts/Type1/"
    FontPath     "/usr/local/lib/X11/fonts/100dpi/"
    FontPath     "/usr/local/lib/X11/fonts/75dpi/"
EndSection

Section "Module"
    Load  "dri2"
    Load  "glx"
    Load  "dbe"
    Load  "dri"
    Load  "extmod"
    Load  "record"
EndSection

Section "InputDevice"
    Identifier  "Keyboard0"
    Driver      "kbd"
EndSection

Section "InputDevice"
    Identifier  "Mouse0"
    Driver      "mouse"
    Option      "Protocol" "auto"
    Option      "Device" "/dev/sysmouse"
    Option      "ZAxisMapping" "4 5 6 7"
EndSection

Section "Monitor"
    Identifier   "GenericMonitor0"
    VendorName   "Monitor Vendor"
    ModelName    "Monitor Model"
EndSection

Section "Monitor"
    Identifier   "Monitor0"
    VendorName   "Acer"
    ModelName    "S202HL"
    HorizSync    30-80
    VertRefresh  55-75
    # 1600x900 @ 60.00 Hz (GTF) hsync: 55.92 kHz; pclk: 119.00 MHz
    Modeline "1600x900_60.00"  119.00  1600 1696 1864 2128  900 901 904 932  -HSync +Vsync

    # 1200x675 @ 60.00 Hz (GTF) hsync: 41.94 kHz; pclk: 65.09 MHz
    #Modeline "1200x675_60.00"  65.09  1200 1248 1376 1552  675 676 679 699  -HSync +Vsync

    # 1280x720 @ 60.00 Hz (GTF) hsync: 44.76 kHz; pclk: 74.48 MHz
    #Modeline "1280x720_60.00"  74.48  1280 1336 1472 1664  720 721 724 746  -HSync +Vsync

    # 1024x576 @ 60.00 Hz (GTF) hsync: 35.82 kHz; pclk: 47.00 MHz
    #Modeline "1024x576_60.00"  47.00  1024 1064 1168 1312  576 577 580 597  -HSync +Vsync

    Option "PreferredMode" "1600x900_60.00"
    #Option "PreferredMode" "1600x675_60.00"
    #Option "PreferredMode" "1280x720_60.00"
    #Option "PreferredMode" "1024x576_60.00"
    Option "DPMS"
EndSection


Section "Device"
        ### Available Driver options are:-
        ### Values: <i>: integer, <f>: float, <bool>: "True"/"False",
        ### <string>: "String", <freq>: "<f> Hz/kHz/MHz"
        ### [arg]: arg optional
        #Option     "ShadowFB"              # [<bool>]
        #Option     "DefaultRefresh"        # [<bool>]
        #Option     "ModeSetClearScreen"    # [<bool>]
    Identifier  "Card0"
    Driver      "vesa"
    VendorName  "Intel Corporation"
    BoardName   "Core Processor Integrated Graphics Controller"
    BusID       "PCI:0:2:0"
EndSection

Section "Screen"
    Identifier "Screen0"
    #Device     "Card0"
    #Monitor    "Monitor0"
    SubSection "Display"
        Depth     24
        Modes "1280x720_60.00" "1024x768"
        #Virtual 1200 675
    EndSubSection
EndSection

Section "Screen"
    Identifier "Screen1"
    Device     "Card0"
    Monitor    "Monitor0"
    SubSection "Display"
        Viewport   0 0
        Depth     1
    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

---

EDIT: Updated with information. This is a VGA cable connected to the onboard video controller. pciconf -lv reports it as:

vgapci0@pci0:0:2:0: class=0x030000 card=0x04381028 chip=0x00428086 rev=0x12 hdr=0x00
    vendor     = 'Intel Corporation'
    class      = display
    subclass   = VGA

It's a brand new VGA cable, but I will try with a different cable. There is no onboard DVI.

Answer 1

Your config has only one ModeLine defined - for 1600x900 resolution - and makes it the Preferred Mode. You can obtain the proper Modelines (determined by Xorg for your monitor) by looking at the log file - usually it is /var/log/Xorg.0.log.

If setting the Modeline does not help, try running X -configure, which will create a xorg.conf.new file with suggested settings. If that also does not solve your problem, you'd probably need to use other display driver.

Answer 2

Depending how new the Intel graphics are, you may also be served by updating to 10-CURRENT which has support for KMS on Intel Sandy Bridge cards and recently X.org was updated to go with this (in the last few days actually).