Hi, if you go to the main producer site ( amd ) and search for AMD Radeon HD 6670 you can find all the information about the GPU( and ofcourse the most valuable information what PSU do you need ) . and here is shortcut for you to get this information : http://www.amd.com/US/PRODUCTS/DESKTOP/GRAPHICS/AMD-RADEON-HD-6000/HD-6670/Pages/amd-radeon-hd-6670-overview.aspx#2
after all these I've got an image from that page for you . and as you can see it says that 6670 supports dual graphic .