PS4 GPU is HD7870 confirmed

[Pemalite]

DietSoap said:

AMD's GCN GPUs have asynchronous compute engines (ACEs). Basically, these ACEs are like additional compute pipelines for GPGPU. You can use them instead of the compute pipeline in the command processor. As a result, the latter will be able to focus on maximum rendering performance. A HD7970 has 2 of these ACEs, it can take care of 2 compute jobs at the same time. PS4 has 8 ACEs and can take care of 8 compute jobs at the same time.

Not exactly.
And I quote:

The GCN command processor is responsible for receiving high-level level API commands from the driver and mapping them onto the different processing pipelines.
There are two main pipelines in GCN. The Asynchronous Compute Engines (ACE) are responsible for managing compute shaders, while a graphics command processor handles graphics shaders and fixed function hardware.
Each ACE can handle a parallel stream of commands and the graphics command processor can have a separate command stream for each shader type, creating an abundance of work to take advantage of GCN's multi-tasking

 

So there aren't two type's of "pipelines" I.E. Shader arrays, but instead two different types of command processors, all the work is done on the same pixel shaders groups.
However, like VLIW the shaders have "branches" which are better suited to some tasks over others.

AMD's Whitepaper on GCN: http://www.amd.com/us/Documents/GCN_Architecture_whitepaper.pdf
That can tell you more than Cerny ever would. :P