There are some substantial rumors that ASUS will bring an ARES III 8 GB Dual-Chip Hawaii Graphics Card to computex this year. This puppy would get two 290(X) chips working in Crossfire and two 4GB memory partitions. With a TDP of over 250 Watt per GPU we can expect the liquid cooled card to have a board power above 500 Watt with a recommended PSU rating of 800 Watt.
A Hawaii XT core features 2816 stream processors, 176 texture mapping units and 64 ROPs. So double that up and boom, 5632 cores. The is being developed under codename Vesuvius, a volcano in Naples, Italy.