Typically, in order to attract a large number of avid consumer , inparticular, video card, manufacturers double and sometimes quadruple increase the amount of memory. In the case of Radeon R9 390, which in the standard version equipped with 8 GB of memory GDDR5, the opposite happened - on sale there were models with only 4 GB of memory.
They can be purchased only in China. Choosing a version of Sapphire, XFX and Dataland (PowerColor). Cost models ranges from $ 305-325, which corresponds to the price of versions with 8 GB of memory on board in US retail chains.
It seems that the appearance of Radeon R9 390 with 4 GB of memory should increase pressure on the position of the video card GeForce GTX 970 NVIDIA serving in the same price range.