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adamkasza
February 7th, 2010, 11:08 AM
Hi,

Recently I've bought a BenQ G2220HD LCD screen. I use Karmic Koala and I have an nvidia VGA card with the nvidia driver (version 185.18.36).

My problem is that at the native resolution (1920 x 1080) my monitor flickers and the image is shifted to the left i.e. a few pixels cannot be seen on the left side and a few cannot be used on the right side. Flickering isn't quite obvious, but it can be easily perceived on a mid-gray background.

My xorg.conf is generated by nvidia-settings:



# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings: version 1.0 (buildd@palmer) Sun Feb 1 20:21:04 UTC 2009

Section "ServerLayout"
Identifier "Layout0"
Screen 0 "Screen0" 0 0
# commented out by update-manager, HAL is now used and auto-detects devices
# Keyboard settings are now read from /etc/default/console-setup
# InputDevice "Keyboard0" "CoreKeyboard"
# commented out by update-manager, HAL is now used and auto-detects devices
# Keyboard settings are now read from /etc/default/console-setup
# InputDevice "Mouse0" "CorePointer"
EndSection

Section "Files"
EndSection

Section "Module"
Load "dbe"
Load "extmod"
Load "type1"
Load "freetype"
Load "glx"
EndSection

Section "ServerFlags"
Option "Xinerama" "0"
EndSection

# commented out by update-manager, HAL is now used and auto-detects devices
# Keyboard settings are now read from /etc/default/console-setup
#Section "InputDevice"
# # generated from default
# Identifier "Mouse0"
# Driver "mouse"
# Option "Protocol" "auto"
# Option "Device" "/dev/psaux"
# Option "Emulate3Buttons" "no"
# Option "ZAxisMapping" "4 5"
#EndSection

# commented out by update-manager, HAL is now used and auto-detects devices
# Keyboard settings are now read from /etc/default/console-setup
#Section "InputDevice"
# # generated from default
# Identifier "Keyboard0"
# Driver "kbd"
#EndSection

Section "Monitor"
# HorizSync source: edid, VertRefresh source: edid
Identifier "Monitor0"
VendorName "Unknown"
ModelName "BenQ G2220HD"
HorizSync 24.0 - 83.0
VertRefresh 50.0 - 76.0
Option "DPMS"
Modeline "1920x1080_60" 173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync
Option "PreferredMode" "1920x1080_60"
EndSection

Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce 6200"
EndSection

Section "Screen"
Identifier "Screen0"
Device "Device0"
Monitor "Monitor0"
DefaultDepth 24
Option "TwinView" "0"
Option "TwinViewXineramaInfoOrder" "CRT-0"
Option "metamodes" "1920x1080_60 +0+0; 800x600 +0+0"
SubSection "Display"
Depth 24
EndSubSection
EndSection


I tried to play with xrandr. xrandr lists the following modes for 1920x1080:



Screen 0: minimum 320 x 240, current 1920 x 1080, maximum 1920 x 1080
default connected 1920x1080+0+0 0mm x 0mm
1920x1080 50.0* 52.0


By default the 50.0 rate is selected and if I switch to 52.0, the screen shifting will be gone, but the flickering will still be there. I also tried to add a mode generated by gtf 1920 1080 60, but with this the 'shifting' comes back and the flickering is still there. I got the same results with cvt too.

So I stuck here. Any help is appreciated.

Thanks,
Adam Kasza

adamkasza
February 13th, 2010, 10:13 PM
Hi all,

Problem solved now. The reason of the flickering was the poorly shielded VGA cable that was provided with monitor. Replacing it with a rather expensive 'extra shielded' dual DVI-D cable solved the problem; now there is no flickering at all.