Had the same issue on 3 machines when changing them to 3850's, make sure your sound hardware is the ac and not the amd one. Took 2 seconds to sort the error
the sound is set too what it should be set as.
ive uninstalled both drivers sound and graphics, installed one and check then the other and checked, tried it in diff order aswell.
as i plug in my speakers or headphones it will play sound for about 2 seconds when the sound device manager is checking jack sensing.
ive never been soo frustrated.
im positive its something simple im missing?