There are 3 cause of this issue: 1- Group loop on your connector 2- VGA cable or VGA output port issue 3- VGA chipset issue But the highest posibble option usually is frist To fix this issue 1 - Follow this article to break the ground loop on your monitor and laptop connectors https://mrgnome.wordpress.com/2009/06/12...-monitor-flicker-laptop-ground-loop-problem-solved/ 2- TESTED ON UBUNTU: If the above solution cant help, try to install TLP and reboot your ubuntu, the noise will be gone. To install TLP, follow this article http://linrunner.de/en/tlp/docs/tlp-linux-advanced-power-management.html Good luck