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My Sys specs : 

**Intel i7-8700k (Coffe-lake),Mother board : ROG(Maximus X Hero)
OS :Ubuntu-Gnome 16.04**

I booted My new PC with Ubutnu-Gnome16.04 , after installation the screen resolution is 1024x768(4:3)--and screen is shown "Unknown Display". I havent installed anything in my new OS.My Monitor-CPU connecting Cable is DP(Pin Cable).

I have tried with "Force create new resolution": 

 a)cvt 1366 768 60
 b)xrandr --newmode "< >"

Then Error throws as :

"xrandr : Failed to get size of gamma for output default". I want perfect resolution to be fit for my desktop screen Can Anyone help me on this

Harish Bodduna
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3 Answers3

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Based on info in this article I've found answer.

You need to add "i915.alpha_support=1" booting parameter to GRUB (Info from here) :

Log in to the system and start a terminal window (Applications->Accessories->Terminal).

In the terminal window at the $ prompt, enter the command: sudo gedit /etc/default/grub

Enter your password when prompted by [sudo]. (If the file /etc/default/grub appears to be empty or does not exist, see the instructions for earlier releases above).

In the editor window, use the arrow keys to move the cursor to the line beginning with "GRUB_CMDLINE_LINUX_DEFAULT" then edit that line, adding your parameter(s) to the text inside the double-quotes after the words "quiet splash". (Be sure to add a SPACE after "splash" before adding your new parameter.)

it should look like this "quiet splash i915.alpha_support=1"

Click the Save button, then close the editor window.

In the terminal window at the $ prompt, enter the command: sudo update-grub Restart the system.

Aron
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marekbrze
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    [here](https://www.phoronix.com/scan.php?page=article&item=coffee-uhd-graphics&num=1) there is more information why it works - – marekbrze Dec 23 '17 at 11:34
  • In short, the i915 driver in the kernel version you have does not have full support for the platform. Enabling it by default has a risk of causing black screens. Thus you have to manually enable the alpha level support in the driver. Later kernel versions won't need this, as the driver has been improved to cover the platform properly. – Jani Jan 15 '18 at 16:13
  • I am on Debian. I do have the same issue. Unfortunately, this answer didn't helped me. Note: There were only "quite" instead of "quiet splash". – Bertram Gilfoyle Dec 06 '18 at 08:09
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An answer I found on the askubuntu forum [1] solved the problem for me:

Open the following:
sudo nano /etc/default/grub

Find the following line, uncomment it and change it to 1920x1080:
#GRUB_GFXMODE=640x480 --> GRUB_GFXMODE=1920x1080

Update it:
sudo update-grub

Then restart your computer:
sudo reboot

[1] https://askubuntu.com/a/1167437/724074

doldnh
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  • Half a great answer! This solved the problem but caused a whole new one, now my monitor struggles to update movements. For example, scrolling down to this part of the screen/page took about 8 seconds (as opposed to 0.5 seconds.) – Display name May 13 '21 at 00:49
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    finally figured out part two > I switched the Nvidia drivers to the open source one and everything is looking great – Display name May 13 '21 at 01:15
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In my case I had nvidia drivers issues after changing system default gcc.

I had only one resolution option (800x600) and I've found a hint on the nvidia thread (https://forums.developer.nvidia.com/t/nvidia-driver-is-not-loaded-ubuntu-18-10/70495/2).

You have your system compiler set to clang/llvm but gcc 7.5 is needed. Please set your cc back to gcc-7.5 using update-alternatives

George Vinokhodov
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