Comment 83 for bug 1348890

setting acpi_osi='' to grub worked for me.
sudo dmidecode -s bios-version && sudo dmidecode -s bios-release-date
UX32LN.202
02/24/2014
and
uname -a
Linux toretto 4.5.2-040502-generic #201604200335 SMP Wed Apr 20 07:37:26 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux