Same problem me too See in DP45SG Mother board.
DP45SG Motherboard Has some Audio Problems. It has a Hardware conflict with Front Headphones and Back panel head phone Slot.
Even if it works for Low Volumes, the board does not support Audio after 1 hour of ooperation even for low volume too.
It also does not Directly support The PS2 to USB Converter when the Board Starts.
When It is Given to Intel For warranty Support a new board was replaced, but still same problem remain, Is there any Solutions to Solve This problem?