Just got a new Lenovo H405, machine type 7723 (this is the closest I have found so far for everything I need). The "sound devices" page displays "HDMI does not plugged in". I attempted many stuff: made certain HDMI is on inside BIOS; updated nvidia drivers as well as Lenovo HD drivers. It at rest shows showing the same message. I have connected the cable properly and I am receiving video on TV, and while I plug this cable into my laptop - I am receiving video as well as sound. Therefore there is no doubt about the TV.