After upgrading LTS from 12.04 to 14.04 I have the same issue. I have a 4 monitor setup with 2 graphic cards. I tried a lot of configruations / drivers, but the only thing that "worked" was completly uninstalling fglrx and connecting 3 monitors to 1 graphic card.
Setup: ------ 1x Radeon HD 6450 -- 2x DVI BenQ GW2750 -- 1x HDMI BenQ GW2750 1x Radeon HD 6450 -- 1x DVI BenQ GW2750 Result --------- Mouse Flicker on the 3 monitor system. No flicker on the 1 Monitor system. Funny thing ----------- When changing to gnome 3 or Xfce the flickering disapears -> Unity Bug? cat /etc/issue -------------- Ubuntu 14.04 LTS lspci | grep -i vga ------------------- 01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Caicos [Radeon HD 6450/7450/8450 / R5 230 OEM] 02:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Caicos [Radeon HD 6450/7450/8450 / R5 230 OEM] -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1278223 Title: Mouse Flickering after adding 3rd Monitor To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1278223/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs