How do I match a mother board to a CPU ?

I want to purchase the Biostar TA 880GU3+ Version 6x.(It has the audio & video chips) And read up about adding a AMD Phenom II x3 720. The #'s all matched on the Biostar site but then I went to the AMD site they did not have that motherboard as a use able option. In fact none of the Biostar motherboards that they mentioned are available. I have been Googling for information and NOTHING. The both have the AM3 socket. Let me know if you have info or where I can get some. Thanks Dennis