The ACEs are effectively the workload setup and dispatch logic that is present in the graphics pipeline, minus the graphics-specific portions. It's somewhat ambiguous as to whether one of the ACEs in Tahiti is the graphics pipeline, but the graphics pipeline can run compute and graphics commands, while the ACEs are limited to the compute subset.
General cache coherency is more the province of the cache subsystem, which GCN has linked most parts of the chip to, including the parts of the graphics portion not explicitely kept separate.
The more interesting idea would be if there were CPU cores were under the ACEs as well as CUs, which at least in theory could be a future direction to take things. ACEs assign contexts and set up the register allocation and flag setup per wavefront assignment, which at a high level is what loading a CPU thread is, absent hardware accelleration of the process.
edit: One could also make an x86 core take the place of an ACE, for a more software-driven approach.
What is the usual performance hit between coherent and incoherent memory access. Some of the rumors I have seen cite 2 different bandwidth numbers. One for "coherent bandwidth" (lower), and one for incoherent. Assuming 8 Jagcores and 1 laptop GPU, what does incoherent access mean ? (Between the Jag cores or between the CPU and GPU ?).
thats not true,
if you read posts of beginning 2012 on this very thread, I was one of the few expecting 4 Gb of GDDR5 RAM for PS4, and I was criticized as being unrealistic...(too expensive)
I was also one of the very few to expect a top of the line laptop GPU for ps4, the idea was attacked furiously with the argument that "laptop top of the line GPUs cant be used for consoles because they cost too much and they come on limited quantity"
There there... [pass hanky to doctor]
The ps3 if DF got it right looks like an interesting device.
With regard to the "secret compute sauce" I could bet on it in fact being part of the main GPU.
We know that for instance the HD 7970 has 2 ACE (asynchronous compute element) so Pitcairn.
Might be good to give a link to a solid ACE resource/reference on the net.