Xrandr displaying "Failed to get size of gamma for output default"

Question

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

Answer 1

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.

Answer 2

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