Codenamed Southern Islands, these next-gen chips will be 28nm (TSMC) based and as the chart above denotes, sitting at the top of the hill is the dual GPU wielding HD 7990. As per tid bits of info on the two Tahiti XT/Pro Cores the card will use, the max stream processor count is estimated to be around 4000 ALU, with the card featuring a TDP of >300W.
AMD Radeon HD 7000 series details leaked :: TweakTown USA Edition