Graphics problem I don't understand: hardware, driver or xorg related?

[heinkel_111]

Hi, on another of my computers I experience a constantly recurring problem. After login and start of the graphical  desktop, it crashes/freezes in a gradual progression, as follows:
1. almost immediately after login i get random "wrong coloured pixels" (short lived and longer lived as in 1-30 secs or so).
2. next phase I get vertical stripes of wrong coloured pixels that migrate slowly across the screen.
3. third phase is a desktop freeze. By now there is a lot of wrong coloured pixels around, maybe more in the windows than on the desktop background. Text in the windows is sometime hard to read.
Strange thing is i can still move the mouse pointer, but i cannot do anything with it. At this point, I can though an ssh from another machine see that Xorg process is running at very near 100%. Processes not directly related to desktop graphics seem to keep running, such as amarokapp (I can still enjoy Gabriel and Dresden as I type this )
This whole crash/freeze process takes about 5 minutes, not more.

The machine with the problem is a pentium 4 running kubuntu dapper drake with all packages updqated as of the day before yesterday. It is equipped with a Point of View NVIDIA GeForce6800 GT graphics card, and the screen I am trying to make it run smoothly on is a Samsung SyncMaster204B, using the digital video interface.
Prior to these problems, I did a major work-over on the hardware and 1) removed the floppydisk (more air for cooling) 2) installed an extra hard disk drive 3) bought that lovely monitor that I had dreamed of for a long time. Althoug I don't see any obvious reason why, it is possible i screwed up on the hardware installation but it did run problemfree for almost a week before all this started the day i moved my /home partition to the new harddrive.

I still think that these are just a bunch of coincidences, and that the problem is software and related to something worng in my xorg.conf, which is posted below, but i just want to keep these less problable options open until they can be eliminated.

my Xorg.conf (for problem computer):

# /etc/X11/xorg.conf (xorg X Window System server configuration file)
#
# This file was generated by dexconf, the Debian X Configuration tool, using
# values from the debconf database.
#
# Edit this file with caution, and see the /etc/X11/xorg.conf manual page.
# (Type "man /etc/X11/xorg.conf" at the shell prompt.)
#
# This file is automatically updated on xserver-xorg package upgrades *only*
# if it has not been modified since the last upgrade of the xserver-xorg
# package.
#
# If you have edited this file but would like it to be automatically updated
# again, run the following command:
#   sudo dpkg-reconfigure -phigh xserver-xorg

Section "Files"
        FontPath        "/usr/share/X11/fonts/misc"
        FontPath        "/usr/share/X11/fonts/cyrillic"
        FontPath        "/usr/share/X11/fonts/100dpi/:unscaled"
        FontPath        "/usr/share/X11/fonts/75dpi/:unscaled"
        FontPath        "/usr/share/X11/fonts/Type1"
        FontPath        "/usr/share/X11/fonts/100dpi"
        FontPath        "/usr/share/X11/fonts/75dpi"
        # path to defoma fonts
        FontPath        "/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType"
EndSection

Section "Module"
        Load    "bitmap"
        Load    "ddc"
        Load    "dri"
        Load    "extmod"
        Load    "freetype"
        Load    "glx"
        Load    "int10"
        Load    "type1"
        Load    "vbe"
EndSection

Section "InputDevice"
        Identifier      "Generic Keyboard"
        Driver          "kbd"
        Option          "CoreKeyboard"
        Option          "XkbRules"      "xorg"
        Option          "XkbModel"      "pc105"
        Option          "XkbLayout"     "no"
EndSection

Section "InputDevice"
        Identifier      "Configured Mouse"
        Driver          "mouse"
        Option          "CorePointer"
        Option          "Device"                "/dev/input/mice"
        Option          "Protocol"              "ExplorerPS/2"
        Option          "ZAxisMapping"          "4 5"
EndSection

Section "InputDevice"
  Driver        "wacom"
  Identifier    "stylus"
  Option        "Device"        "/dev/wacom"          # Change to
                                                      # /dev/input/event
                                                      # for USB
  Option        "Type"          "stylus"
  Option        "ForceDevice"   "ISDV4"               # Tablet PC ONLY
EndSection

Section "InputDevice"
  Driver        "wacom"
  Identifier    "eraser"
  Option        "Device"        "/dev/wacom"          # Change to
                                                      # /dev/input/event
                                                      # for USB
  Option        "Type"          "eraser"
  Option        "ForceDevice"   "ISDV4"               # Tablet PC ONLY
EndSection

Section "InputDevice"
  Driver        "wacom"
  Identifier    "cursor"
  Option        "Device"        "/dev/wacom"          # Change to
                                                      # /dev/input/event
                                                      # for USB
  Option        "Type"          "cursor"
  Option        "ForceDevice"   "ISDV4"               # Tablet PC ONLY
EndSection

Section "Device"
        Identifier      "NVIDIA Corporation NV40 [GeForce 6800 GT]"
        Driver          "nvidia"
        BusID           "PCI:1:0:0"
EndSection

Section "Monitor"
        Identifier      "SyncMaster"
        Option          "DPMS"
EndSection

Section "Screen"
        Identifier      "Default Screen"
        Device          "NVIDIA Corporation NV40 [GeForce 6800 GT]"
        Monitor         "SyncMaster"
        DefaultDepth    24
        SubSection "Display"
                Depth           1
                Modes           "1600x1200" "1280x1024" "1024x768" "800x600" "64
0x480"
        EndSubSection
        SubSection "Display"
                Depth           4
                Modes           "1600x1200" "1280x1024" "1024x768" "800x600" "64
0x480"
        EndSubSection
        SubSection "Display"
                Depth           8
                Modes           "1600x1200" "1280x1024" "1024x768" "800x600" "64
0x480"
        EndSubSection
        SubSection "Display"
                Depth           15
                Modes           "1600x1200" "1280x1024" "1024x768" "800x600" "64
0x480"
        EndSubSection
        SubSection "Display"
                Depth           16
                Modes           "1600x1200" "1280x1024" "1024x768" "800x600" "64
0x480"
        EndSubSection
        SubSection "Display"
                Depth           24
                Modes           "1600x1200" "1280x1024" "1024x768" "800x600" "64
0x480"
        EndSubSection
EndSection

Section "ServerLayout"
        Identifier      "Default Layout"
        Screen          "Default Screen"
        InputDevice     "Generic Keyboard"
        InputDevice     "Configured Mouse"
        InputDevice     "stylus" "SendCoreEvents"
        InputDevice     "cursor" "SendCoreEvents"
        InputDevice     "eraser" "SendCoreEvents"
EndSection

Section "DRI"
        Mode    0666
EndSection

Section "Extensions"
        Option "Composite" "Enable"
EndSection

[askrieger]

Re: Graphics problem I don't understand: hardware, driver or xorg related?

I don't know if this is the cause of your problem, but I noticed that you didn't have any lines in your xorg.conf concerning either the range of acceptable Vertical Refresh rates and Horizontal Sync Frequencies, or a set of acceptable modelines for your monitor. Since it is a fairly new acquisition, you probably haven't lost the owner's manual yet , so I would think the easiest thing to do would be to put in the appropriate frequency ranges.

The rates are actually on the Samsung website: Horizontal Sync = 30 - 81 kHz, and Vertical Refresh = 56 - 75 Hz. Also, since it's a flat panel, you could remove all screen sizes other than 1600x1200 from your display subsections. If that makes it hard to read the fine print in M$ EULAs, you can increase the font size, rather than changing the screen resolution.

[heinkel_111]

Re: Graphics problem I don't understand: hardware, driver or xorg related?

Hi askrieger I am sorry for my late reply but it was because my access to these forums were bookmarked on the troubled computer. I have posted on some other forums were there was more feedback quicker, besides doing lots of testing myself.
Indeed my "cleaner" xorg.conf (written by hand rather than configure-script") had much fewer modelines, but I think it is a good idea to keep especially 800x600 in there as it is a much used fallback alternative for graphic intensive applications(ie. in games etc). I don't know if it is needed to enable a "fallback" or not, but certainly it doesn't really harm much if you get a very blurred interpolated image once in a while, it will only make it easier to weed out the problems if it keeps on running instead of crashing.

As for the graphics problems, it is now confirmed that the root cause of all evil is a Point of View 6800 GT card with serious problems. It has come to the point where it produces output almost half of the times I try to boot the computer. Trying to fix this hardware problem by improving, amongst other (software) settings, my xorg.conf file, of course lead to a lot of problems that weren't there in the first place.

An example of what happened, the BusID for the graphics card was lost from the xorg.conf at one time, this I think was caused by running glx-nvidia-configure or wahtever it is (will look it up later) at a time when the graphics card was not functioning, I guess.

Status as of today, one graphics card lost. Replacement may be covered by the guarantee. At another forum several other users reported that they had received new ones from the retailer after experiencing exactly the same sequence of problem, ie random noise -> coherent noise -> freeze/lockdown). In addition, I feel I am getting quite more fluent in xorg.conf lingo and structure, and once i receive a new graphics card (guarantee or not) I will write the new one with feather pen and ink on pergament.... :P (In addition, I have learned how to dissasemble the cooler unit on the gfx card. After some de-dusting the temperature on the card dropped almost 20 degrees. Guess I should have done that while the card was still functioning.

I have a temporary fix already planned. I need to learn how to configure my problem, computer as a file/application server, to work without graphics card. I guess this means I must disable the graphics card, monitor and screen in xorg.conf? I will post another thread about that, I think. What I like about my plan is I can just make this computer run a dual head display, use x-forwarding from the problem computer and tickle a few of my menu entries so that for instance kontact, ktorrent, and media players with 32-bits windows codecs runs from the "problem computer" (this box contains an AMD 64X2 and it will never run 32-bit). This X-forward solution will be almost just as good as having that computer with a graphics card, the only problem is it is not as fun to invite a freind over for a night of multiplayer gaming.

When all this is done, I will file a report in my blog.