Original post by: Michael Anderson ,
Greyed out speakers may mean that the sound out is "locked" in optical mode. This can happen even if you never used the optical mode. Try put a ordinary audio plug in the sound out connection. Rotate and carefully move it in/out, left/right. A total reinstallation of the system may help too. Otherwise one may use a USB sound gadget. There are some fairly cheap ones on the market. Changing the motherboard seems a little bit over the hill...