After replacing a single core A64 with a dual core cpu on the Ultra-D, the board refuses to POST, getting stuck at the last red debug light. The board has the 6/23 bios, so DC support is there, and all the other components are the same. After trying different video cards, different mem, various mem slots, resetting CMOS to no avail, you then finally put the original single core cpu back on the board, and it still refuses to POST, even though the same setup worked fine before. I've seen this happen to 2 people recently, so what gives?