My display was at a very low resolution (1024x768) , so I added a higher resolution manually using xrandr
for my BENQ G2420HDB, which is supposed to have a native resolution of 1920x1080. I succeeded in changing the resolution, but subsequently, the display did not fill the screen; the edges of the monitor were black. Pressing the "Auto" button on the monitor made it worse, such that part of the display was invisible. I manually changed H. Position, V. Position, and Pixel Clock. This has made the black edges smaller and I can see the entire display, but now I get flickering when I have (rapidly) moving images (scrolling, changing desktops, video, etc.). My monitor is connected with a VGA-DVI-adapter to an AMD/ATI RV620 HDMI Audio (Radeon HD 3400 Series) graphics card.
To install the new mode I used:
xrandr --newmode "1920x1080_60.00" 173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync && \
xrandr --addmode DVI-0 1920x1080_60.00 && \
xrandr --output DVI-0 --mode 1920x1080_60.00
Subsequently, xrandr
shows:
$ xrandr
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 8192 x 8192
VGA-0 disconnected (normal left inverted right x axis y axis)
HDMI-0 disconnected (normal left inverted right x axis y axis)
DVI-0 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
1024x768 60.00
800x600 60.32 56.25
848x480 60.00
640x480 59.94
1920x1080_60.00 59.96*
What may cause the symptoms I described? Is the resolution I'm trying to set wrong? Or does this point to a hardware problem with graphics card, monitor, or perhaps even the adapter?