Well, after searching and reading some posts on other forums, it seems this is a mystery.
But, best I can tell Biostar doesn't test with any opterons so the bios may not have recognized.
So, I decided to buy a Asrock 939 board with that ULI chipset. Seems alot of people are using it, so I'll give that a go and send back or keep the 6100 for something else. (I told Newegg to cancel it, but it may be too late)