I have read this question - Brightness problem on Ubuntu 18.04 and this is my set up -

 Linux gansub-OptiPlex-7050 4.15.0-38-generic #41-Ubuntu SMP Wed Oct 10 10:59:38 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

and this is my graphics card -

00:02.0 VGA compatible controller: Intel Corporation HD Graphics 630 (rev 04)

   description: VGA compatible controller
   product: Intel Corporation
   vendor: Intel Corporation
   physical id: 2
   bus info: pci@0000:00:02.0
   version: 04
   width: 64 bits
   clock: 33MHz
   capabilities: pciexpress msi pm vga_controller bus_master cap_list rom
   configuration: driver=i915 latency=0
   resources: irq:126 memory:f6000000-f6ffffff memory:e0000000-efffffff ioport:f000(size=64) memory:c0000-dffff

Since yesterday I have screen flickering as well as screen dimness and occasional unable to boot problems. I did a diagnostics check and all tests turned out successful. What usually happens is that the screen starts to flicker, then dim itself and then dies. When I try to reboot it gets stuck. I did try

   ubuntu-drivers autoinstall

But the problem persists. Since there maybe so many approaches as per the answers available on this site I would like to know which approach I should take.


I made the following change to /etc/default/grub and it is still flickering.

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

Based on this Q/A - Ubuntu 18.04 screen strobing here is the output of xrandr

Screen 0: minimum 320 x 200, current 1600 x 900, maximum 8192 x 8192
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-2 disconnected (normal left inverted right x axis y axis)
DP-2 connected primary 1600x900+0+0 (normal left inverted right x axis y axis) 432mm x 236mm
 1600x900      60.00*+
 1280x1024     75.02    60.02  
 1152x864      75.00  
 1024x768      75.03    60.00  
 800x600       75.00    60.32  
 640x480       75.00    59.94  
 720x400       70.08  
 HDMI-3 disconnected (normal left inverted right x axis y axis)
 DP-3 disconnected (normal left inverted right x axis y axis)

So I am not sure whether I should change the refresh rate to stop the flickering.

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