just wait official announcement from amd. the rumor has it going since last year Q4 then postponed to this year Q2 because back then the story was amd intends to make more profit with 7k series before releasing 8k series. then amd themselves debunk the rumor about Q2 release for their next generation and with right now with amd already stressed out that 7970Ghz will be their top offering throughout the year a new rumor something will come out in september/october time frame with the performance enough to beat 780 no less.
so at this point just wait for amd official announcement