According to the data that have come to light during these days, the next NVIDIA GPU GP104 (Pascal) will have two kind of PCBs, one for GDDR5 memory (Base) and one for GDDR5X memory (Premium), due to different packages of these memories.
The first one will be equipped with the GP104-200 GPU (It will have some disabled CUDA Cores). The last one will be equipped with the GP104-400 GPU (Fully enabled GPU).
NVIDIA has already shown a similar strategy (e.g. GK104), but this time the differences will be most marked. We think that the GP104-200 will equip the GTX1080 and 1070 cards, and the GP104-400 will equip the Ti cards (After the summer).