Your viewpoints are perfect and fully agree with,but sometimes I think that if the APU will in fact succeed, because although the idea is excellent to marry cpu + gpu + memory controller etc on the same die (this is much more I know ..) perhaps i'm wrong here...I have the impression today and even next year the APUs is still very incipient and too ambitious to become something much more eficcient to compensate more powerfull the current paradigm CPU and GPU "separates,singles etc.
Another interesting point that you touched,were the chances of bugs (similar to the multiplier in the Intel pentium or even worse damaging memory accesses etc) in these new processors coming from AMD ... and imagine if something similar occurs next gen consoles on the production line?
I personally would prefer they used something that was had already tested and approved and if customized (put something extra on SIMD,die shrinks to 28nm,disable or retired pcs things etc.) cpus and gpus for next gen consoles maybe could be very interesting ... my "dream console" is something like quad Athlons II + Radeon HD 5850 (on the paper ...almost 2.1 TFlops ).
The big advantage I see for Sony with a SoC is cost.
Especially if they were to go with pretty much off the shelve Kaveri.
They already reduce (supposedly) the R&D by going with AMD which provide complete solution CPU+GPU.
Prior APU was not tempting but kaveri is another matter. By the way I'm impress that they plan to have such a jump in GPU power and still keeping the TDP at 100W.
I can't answer you on the benefits of an APU vs a two discrete part of the same power. I've read here and there (like pretty much every body can) that low latency communication between the CPU and the GPU could have positive effects on perfs but I can't tell more. For all I know it could be misunderstanding from my side of theirs.
I mean there is priority in job submitted to the GPU but as I see a GPU it could be a while before you get the result. Still if they were way to save the round trip to memory (GPU writing to it and then the CPU when informed than data are there as to read for the RAM...) but will Kaveri do that? (will the GPU L2 be coherent with the cores ones? I would say no).
Intel seems do be able to pull that to the benefit of their driver team (... don't laugh
).
There are benefits in power consumption you avoid to duplicate the memory controller for example. But it's not free you have to share bandwidth.
I believe that in the PC world AMD efforts are hold back by the memory type, APU are bandwidth starved.
You have only one chip to test etc. it makes sense.
How much consume an Athlon II X4? I would say quiet a lot, Let say they have a TDP of 65 Watts.
Then you have not a hd 5850, it consumes a lot I guess. a HD7850 may be a better base (or a 6850 using the 45nm lithography). That's plenty of Watts. That's a gpu with a 256 bits bus. that's two memory pools. etc.
Say a fairer (but hypothetical) comparison would be a Athlon III X4 same speed but using 32 nm lithography. Let say it consumes 45 Watts.
Then you have a 7770 or something with more CU enable but clock lower so its power consumption is in between the 7770 and the 7750 (45 and 75) so let say 60 watts.
The whole thing consumes 105 watts and there is 4 chips of gddr5 and 4 chip ddr3 consuming extra power. you need an a bit more complex board. You need two cooling solutions, etc.
Now what a kaveri with gddr5 would come close of that but cost most likely less. I beileve that there is no magic the GDDR5 might up kaveri power consumption, there might be trade off, in CPU speed, in mem controller speed, they may want to let the GPU clock untouched though but who knows (and it's not like 10% would change the big figure).
It might perform worse but from a cost pov, It may lead, may be not an awesome difference but on million units.
For the bug I'm may be overly dark as the early phenom incident is old now and Stream roller may either tweak K10 architecture or the BD cores v3, in both case AMD should would not be in unknown territory. It still clearly a risk, with Kaveri release no one know when in 2013.
Honestly Kaveri is not an amazing proposal but played right at the righ price (so pretty cheap) it may do Sony a lot of good, especially if they (/rumors) are right about missing 2013.
Kaveri will keep with pC games for a long while, no matter what MS aims at, could it be the moon.
EDIT
WRT to the hd 6670 / 7670 by AMD own numbers HD 5670 costs 75$ so it's cheap but not that much more like margins are terrible in that price range.
Edit 2 not amd number but looks like serious estimate. Link might come tomorow
