I'm posting this with strong hesitation here as this is a wccftech article. Please take this with a grain of salt.

"So my question is, what do we still not know regarding the Xbox One? The answer is what could possibly be a super fast discrete graphics core stacked inside the main SOC itself. I know it sounds fishy when you first hear about this and the first thing to come up in your mind are, how did anyone not notice this in the first place? or Does AMD or Microsoft have the technology to even manage something like a stacked wafer design? Well, the Xbox architecture hasn?t been in works for just recently but it has been under consideration since some time.
The technology does exist and first appeared in an AMD slide back in 2009. AMD has bet everything on their APU design and if they want to remain competitive on both x86, GPU and Compute sectors than their all-in-one SOCs are their best hope. Back in 2009, AMD revealed a slide that showcased their future potential designs for APUs, the slide starts off with a common PC setup we found these days that includes a discrete GPU and an x86 CPU. Next up is the first APU design which shows the GPU and CPU on a single die, after this we see optimization between both units which include a coherent memory structure and various other improvements which are referring to the Heterogeneous System Architecture which we would see in the next generation of APUs. The last stage is the most critical which involves exploitation of what more could be done and that is only possible through a full fusion of the CPU and GPU knowned as APD (Accelerated Processing Device)."


Read more: http://wccftech.com/rumormicrosoft-x...#ixzz2drGPWdkq