Audio output over HDMI is only supported when the graphics card of the notebook or desktop computer supports audio output over DisplayPort. Several on-board graphics adapters such as Mobile Intel 4 Series Express Chipset in Notebooks (i.e. Dell E6400) do NOT support audio output over DisplayPort, even when HDMI support (Intel High Definition Audio HDMI Service) is installed for audio controllers. In such instances a separate audio connection has to be set up.
