It's actually easy to tell if they did have those features or not. If they did, the support would be listed in giant letters as a special feature, particularly since they would need to pay for the licensing of DD or DTS to be added to the board, along with the decoding chip. DD and/or DTS are still fairly rare features on mother boards, although some are adding them now. I have an old socket 775 Intel mother board that had DD 5.1 decoding by some miracle, although the "driver" (decoding software) could be glitchy for some users, apparently.
BTW, the answer in none.
I always laugh at the "HD Audio, 7.1 Channel Support!" marketing line seen on mother boards. Sure, it has 7.1 channels, but what is feeding those channels, what is the source? Of course, SPDIF output is unrelated to that, but if DD or DTS decoding was available, it would be routed to both of those output types.