Other source reveal that this card is the first in the world with stacked memories (2.5D interposer stacking), where the memory chips are placed at the side of the graphics processor on the same substrate. The idea behind this is to streamline communication between both parts and provide both a higher efficiency and a significantly higher bandwidth when compared to GDDR5.
Another interesting detail (if true) is that the card will have a closed water cooling system much like the R9 295X2 has.
We can't wait to get our hands on this! Stay tuned for more details as they arise.
Source: www.sweclockers.com