So
Nvidia introduced their Maxwell architecture last week, albeit in a smaller form with the emphasis on
doubling the performance per watt.
Any ASIC that has a very good perf/W is an ideal candidate for being a console GPU since the console vendors have a much smaller TDP budget compared to PCs. So obviously, this is an theoretical exercise about what if Nvidia had supplied a GPU twice the capability of the GM107.
I took the GM107, doubled it and ran the numbers at 800MHz. So there are obviously some assumptions in place, for example a doubled GM107 would be ~270mm2 rather than 296mm2 (148mm2 x 2), the doubled GM107 running at 800MHz would produce a peak TDP of around 100W rather than 120W (60W x 2).
Regarding the CPU, since we're going the Nvidia way, let's pick the top Bay Trail from Intel. Performance would be mostly comparable to Jaguar as per Anandtech. I believe there are 4 core desktop versions of the same that would end up with slightly lesser TDPs than Jaguar. Anyway, these cores wouldnt take up much area, maybe in the range of 50mm2 at the most.
So how does the theoretical double GM107 (@ 800MHz) stack up?
In terms of die area, we would be looking around the same ball park as the PS4 GPU (346mm); 270mm2 + 50mm2 = 320mm2 for this combination. In terms of power consumption, Bay Trail is more efficient than Jaguar and a doubled GM107 would also most likely draw less juice but probably by a whole lot less; 100W + 5-10W = 105-110W. Compared to PS4's peak power consumption, its about ~25% less.
So we have a very similar overall spec setup but with slightly less peak power consumption levels. The die area is also in the same range but with added board complexity (separate CPU/GPU die). Also doesnt take into account of disabling any of the functional units for the sake of redundancy or yield purposes.
And not to forget it would be mean not launching in '13 with the amount of launch units they did. Overall I think, even considering Maxwell's superior (effficient) architecture Sony's combination of CPU+GPU in the PS4 is very competitive and the best decision they could have taken for the launch window they had in mind.