The new report comes from Sweclockers.com, which state that the new AMD graphics card, based on the Fiji XT GPU, could end up with Radeon R9 380X branding rather than the R9 390X, as rumored earlier. According to the same report, the R9 380X will pack 4096 Stream Processors as well as 4GB of the new 2.5D stacked High-Bandwidth Memory.
According to the number of Stream Processors, the upcoming Fiji XT based graphics card, whatever AMD decides to call it in the end, will be around 45 percent faster than the R9 290X, and that is without taking into account architectural improvements and performance improvements of the new Hynix High-Bandwidth Memory, which promise both higher efficiency and higher bandwidth.
Earlier rumors suggested that the Fiji XT graphics card will have a TDP of somewhere around 300W, which suggest that it might feature a closed-loop liquid cooling system, something that we have already seen on the AMD Radeon R9 295X2 dual-GPU graphics card.
In any case, these are still rumors and should be taken with a grain of salt, but Q2 2015 launch timeframe will be really good for AMD if they manage to pull it off.