Sorry I added more to my post, but fundamentally unless they work seperately (in parallel) you just cant add their bandwidth together like he did. Considering what can populate the eSRAM its very unlikely not to be the DDR3 and if thats the case its nowhere as qualified as the calculation he just made - its a joke to describe it as a headline like he just did as far as I understand it...
ps3ud0
It's interesting. I agree you can't just add two sets of bandwidth together unless he's saying they have a way for the CPU/GPU to draw from both sets of memory simultaneously in parallel as you say, in which case it still doesn't quite work out like that but it could be an interesting scenario if true as it gives you a way to have sustained bandwidth for some elements and significant burst bandwidth for others.
The other thing is if the eSRAM is effectively acting as a cache. Although there's not a lot of it the CPU isn't drawing from memory constantly so although the slower main memory needs to keep it topped up it could mean that the CPU has a decent supply of RAM available to it at the eSRAM speed. For example if the CPU empties the eSRAM in one "tick" and doesn't request anything more for a further 4 ticks there's enough time for the slower main memory to keep the eSRAM topped up ready for the next call. Of course you're never going to get full bandwidth as there's at the very least an inefficiency in predictive caching, still, again it'll be interesting so see in practical terms linked with the faster CPU and HAS bandwidth of 30GB/s vs 20GB/s.
I wonder what the driver and API optimisations look like on the two consoles, especially for launch. We all know a dodgy/good driver can make double digit differences to performance.
I still think the PS4 will be quicker but as I mentioned before, I genuinely don't think it will be anything near the "50% faster" being bandied about.
None of which really matters other than I think if the performance difference ends up being down to 10-15% real world we're unlikely to see any significant "enhancements" to PS4 versions of cross platform games with a relatively small performance increase, although first party games and exclusives would still take advantage of it I presume.
If you don't have a reason to buy X1 there's still a lot of wisdom to say all other things being equally you may as well get the more powerful console even if it is "only" say 15%, you may as well have it.
Despite the all the bitching backwards and forwards I really don't think there is a "bad" console choice this time. I do have to say though I'm still a little concerned that both consoles whilst "okish" for now but may not age well in 5 - 7 years time.
**Edit** I've just had a look at the hotchips stuff again and it occurs to me in the SoC schematics the eSRAM doesn't seem to sit between main DDR3 RAM and CPU at all, if anything it looks as if it sits between GPU and Nortbridge *confused* although it does have a mystery direct line connecting to CPU. Nope, still no idea what's going on with the eSRAM!

Someone with a bit more experience have a look please, my little brain has just fried itself trying to work out whats going on and what, if any implication there could be for the eSRAM interfacing with the GPU rather than CPU.