M17x-R4 "no audio output device is installed" error

Over the past 2 weeks I have been having more and more issues with my M17x-R4 Alienware laptop. First the screen died. Then the wireless card died. And now there is no sound and when i hover over the sound icon on the taskbar all I see is: "no audio output device is installed". i have had a Dell technician out for repairs 3 times. Motherboard has been replaced twice. he has taken the entire laptop apart and reassembled it. And the sound still does not work. The BIOS has been updated multiple times, drivers been reinstalled multiple times. Everything has been checked by myself, Dell phone and online tech support and the technician who came out 3 times. Has anyone else has a resolution to this issue? the technician recommends that I request a replacement computer as he can't fix it. Not impressed to say the least.