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Comment by cptskippy | Hacker News Reader

I see HBM evolving into an external cache with off substrate RAM eventually working it's way back into cards.

I think you're wrong. Everything in history to date with semis has been focused towards integrating more on chip, or at the very worst, on package. This puts the memory as close as it can get to the chip without driving the chip's cost up astronomically. There's absolutely nothing to suggest they'll de-integrate moving forward.

The biggest problem after this is how much the GPU and CPU have to fight over main system memory, which really brings us to the end game of GPUs altogether. Sooner or later there won't be room enough for both in the picture, your single heterogeneous core or MCM will have both a CPU and GPU on it (and probably a half a dozen or more application-specific accelerators).

I wasn't suggesting there would be any disintegration. Just that off substrate memory will be reintroduced in-addition to HBM.

If you need a point of reference take a look at L2 cache. It was originally chips on the motherboard, then with the PII it was put on a Processor Card, then with the PIII it was eventually integrated into the Die.

The exact same thing happened with L3 cache.

Yup. Memory sticks are the new tape (in the volatile storage hierarchy). Definitely potential for (re-)proliferation of NUMA optimizations.

The questions are whether G/CPUs have:

- multiple or single SKUs for on-package RAM capacities

- addon RAM ability via sticks, sockets and/or surface-mount

I assume there will be multiple SKUs for on-package RAM capacities. Neither Intel or AMD has ever had qualms about adding more SKUs to their lineup.

It would come as no surprise if addon RAM became a feature of the higher end CPUs (e.g. i7, Xeon, Phenom, whatever)

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