Vega Mobile, with HBM2
The graphics strategy in notebooks is bifurcated for AMD. On one side, their Mobile APU business takes care of the low-end of the market. The recent business relationship with Intel to sell graphics chips for Intel’s high-end mobile processors means AMD has a business on that side. The big hole in the middle is for notebook customers that want discrete graphics. After a couple of years of large Polaris based designs using GDDR, AMD is bringing Vega to this market.
As far as AMD were prepared to announce, a single Vega Mobile design is being prepared, which might be subject to binning based on compute units. The full amount of compute units in the chip has not been made publicly available, however it measures basically half of the full Vega 64 chip next to it. This would normally suggest a 32 CU chip, however there are a number of front-end elements required which have a fixed size – compared to the Intel 24 CU chip for the Intel with Radeon Graphics processor, this chip seems to be of similar size, if not bigger.
What we do know about the Vega Mobile processor is that it is paired with 4GB of HBM2, using an embedded interposer to give an overall z-height of 1.7mm. This is AMD’s second or third generation of interposer technology, and it has come a long way since Fiji: the interposer is tight along the dimensions of the GPU and HBM, but it is also embedded into the PCB. The embedding allows it to reduce the height, making it a better fit for ‘thin and light’ mobile platforms. The interesting correlation here is that at 1.7mm, it matches Intel’s EMIB implementation which is also 1.7mm. This caused two theories: either AMD is using EMIB (it isn’t), or it means that the perceived z-height benefit from using EMIB might not exist. The latter is true: AMD has unequivocally confirmed that it is using an interposer, and does not have access to Intel’s EMIB.
Ultimately AMD created more questions and answers with this announcement. Nothing was said regarding power, price, expected CPU/GPU combinations, or which notebook partners they have ready to use it. The only element to the discussion was that the chip will enable VR-capable notebooks, support HDMI 2.1 variable refresh rates, and will be coming in 2018. (Not to be all Maudlin, but watch out for the GPU manufacturer that puts three on a graphics card and sells it to miners.)