Comment 6 for bug 1525554

My two cents,

you have some recent hardwares but use quite old kernel. Your issue is expected, and the solution is to use recent release/kernel with recent hardware.
 Either dist-upgrade (or better do a fresh install to avoid possible settings conflict disturbing the system) to at least wily or xenial (which smoothly works, even if its a development work still on going, blah blah ...); or test trusty + kernel 4.3 if you are afraid by the previous proposal.

 http://kernel.ubuntu.com/~kernel-ppa/mainline/