The last information about graphics solutions Pitcairn states that these cards will be based on VLIW4 architecture , and will be available in December this year under the suggestive names of Radeon HD 7870 and Radeon HD 7850.
Associate note that apart from Tahiti, belonging to the new architecture GCN will be able also Pitcairn, but they will come no earlier than March or April next year. According to asssocaite Tahiti XT video card $ 500 will be released in January, in February Tahiti Pro $ 400, and in March and April will be released Pitcairn XT ($ 300) and Pitcairn Pro ($ 200), respectively. All these graphics processors will be released on 28 nm technology.
At least the older video cards Southern Islands will get a 384-bit bus, which implies an increase of up to 3 GB of memory. This graphics solutions series support both memory types XDR2 , requiring a much more lower bus.