[arch-general] System freeze when powering down.

Hi there, The hardware is Asus K501UX running linux-4.5.0-mainline from aur and a GNOME desktop. The problem is the system freeze when it is powering down (not always but very often). See attached files for logs from properly (power-down-ok-tail.log) and improperly (power-down-fail-tail.log) finished power down sequences. Any clues what should/could I do to fix the issue? Let me know if more information is needed. R.