Did you ever find resolution to this problem? I have the same issue, except my sound has never worked. I've tried Windows 8 and Ubuntu, both appear to be outputting sound but no sound comes out. I've tried front and back panels, with known good speakers and known good headphones. I've disconnected the front panel audio, tried every driver/BIOS switch combination.... Am I just an idiot (possibly) or does Intel have some bad motherboards out there?