DDR5?

DDR has gone downhill. The dance pads were shoddy, and this Kinect stuff is even worse.

Yes I'm joking

It stands for Gigabuttocks.

Acert = Ace Right = Ace is Right. So yes, I am me being me, which is Ace is Right. Glad we all agree on that!

Ok, now that we cleared up that you meant GDDR5 ... different gen, different "design pressures" and bottlenecks. A unified pool is an advantage if two competing systems have the same memory and the memory is being saturated by a high bandwidth client, e.g. the PS3 had a split pool, horrible transfer between them, and the GDDR3 was saturated with RSX fill rate. The 360 which had one pool and all fill rate bandwidth isolated on the eDRAM was a big win.

Those things may not be an issue next gen.

It is too early to say if GDDR5 is better than DDR4. If the DDR4 also has eDRAM (full cache, not a simple ROP buffer) or better 128-256MB stacked memory then a boatload of DDR4 and a very high banwidth pool would be better in most situations.

Some things to consider. GDDR5 is on the downside of its EOL and won't drop a ton in price. It is currently 4x as expensive as DDR3 -- you can get 8GB DDR3 for the price of 2GB of GDDR5. DDR4 will be more expensive than DDR3 initially BUT will quickly drop in price as volume increase. It also has better bandwidth and lower power usage. Also a 256bit bus DDR4 is over 50% of the bandwidth of 2GB of GDDR5 but 400% the size.

Looking at high end GPUs (e.g. 2TFLOPs) I would choose 8GB of DDR4 (lets say 70GB/s to be low end conservative) with a 128MB eDRAM (>256GB/s) cache over 4GB of GDDR5 (probably about 150-190GB/s at best for a high end design). The 128MB workspace with that sort of bandwidth really solves a lot of problems and then having over 2x the content in RAM instead of optical opens up a lot of better caching solutions.

But the more I think about it a 1TFLOPs GPU (think Cape Verde class) with a 4 core CPU and 4-8GB of DDR4 seems likely. Cape Verde is happy with 70GB/s of bandwidth. A SoC APU will be large enough for a 256bit DDR4 bus to allow the bandwidth needs to be met. Pretty balanced, lower end, design. They will target 720p and keep parity with the top end PC games with some "optimization" (read lower IQ) and lower resolution, 30Hz and call it a day.

No expensive GDDR5.
No expensive eDRAM.
No expensive Stacked Memory.
No large, hot GPU.
No wasted silicon in CPUs that give a % in performance returns.

But they will have a lot of slides emphasizing Gigabuttocks to make Phaethon happy!

And he didn't ask for your permission?

I hypothesize that the gigabit bandwidths of the coronary interpersonal diametric properties have transfixed new matrices in congruent incorrigibility by duplicating semi-transparent extraneous oxidized crystals.