My board is a GA-965P-DQ6 Giga-Byte and the latest and greatest Cats according the giga-byte website now add Crossfire support. On the ATi site it reccomends i get another x1900GT. Master card not needed. But i remember when Crossfire first came out you could mix cards models, but with the latest crossfire it seems to have changed and i have not been keeping up to date. Any help would be great.