We have revealed in advance that the new AMD cards will be shown during the Computex 2015 (link) and that AMD is ironing out the Catalyst drivers before the presentation (link). Now, I got to know that the high end Radeon 390X (Fiji XT), a single GPU card, can sport 8GB of HBM memory (so, there will be two version of this card, one with 4GB of HBM and one with 8GB of HBM).
Thanks to the joint effort of AMD and SK Hynix, the Fiji XT GPU can manage 8Gb of HBM through the use of a new technology called “Dual Link Interposer”. This new interposer can double the quantity of HBM usable. We will know more about this technology during the next Computex.
At last, the dual GPU card based on Fiji XT is a prototype for the moment, not ready for the sale.