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Comment by DoctorOetker | Hacker News Reader

It's still unclear to me: the shortage is semiconductor boules / wafers? or the shortage is semiconductor fab process step availability?

As long as the discussion seems focused on memory, I'd suspect the latter, but if its really the semiconductor boules/wafers, then I'd expect the boule growers to profit, not the memory makers, who just pass on the cost.

So which is it?

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It’s fab capacity. Fwiw dram is different enough that fabs are not transferable between dram memory and other usages. It’s nice to think ‘wow if they made the current 10nm dram on the latest 2nm processes it’d be much faster’ but it doesn’t work that way. The specific size is needed for the capacitance. Sram can be made on fabs that make other circuitry since it’s transistor not capacitor based but is less dense.

Dram is just extremely specialised.

I know the differences between SRAM, DRAM, ...

I asked for evidence different people keep feeding me opposite stories: one insists its not fab capacity but wafer competition, with a recent article claiming HBM3E takes 3 times as much wafer area per bit than LPDDR5X. Others tell me the complete opposite: its fab capacity, not wafer shortage.

Do we have citable references to ground either set of claims?

I believe those are two ways of describing the same thing. If you're able to book some fab capacity, that means you get to decide what the fab does with the next wafers in the queue.

From your sibling comment, I think you're interpreting the 3x HBM stat as contributing to making wafers scarce. It's more that the next wafer to be processed in a fab is especially precious, making the opportunity cost larger. The beach sand remains plentiful.

so the bottleneck is the fab, again

There is a good article (featured on HN a couple of days ago) that explains the issue: https://davidoks.blog/p/ai-is-killing-the-cheap-smartphone

And that article is contradicting other voices. If that article were correctly identifying the bottleneck as wafer shortage due to switching to HBM, why is everybody discussing the memory makers instead of the boule growers. Memory makers can expand operations all they can, which makes no sense if wafer supply doesn't follow, and the article is suspicously light on semiconductor boule / wafer mfr's.

So which is the bottleneck: fabs or boule growing?

also consider how most solar panels are monocrystalline silicon, how credible is silicon wafer shortage ... really? there is so much disinformation in this market...

This covers it pretty well https://news.ycombinator.com/item?id=48229319, TLDR -memory for AI uses more wafers from same production line as other memory and is more profitable, building new fab very risky historically for companies. The companies have cut production of other memory to favor memory for AI and the market for memory for AI is still unfulfilled so prices still go up for customers of every type.

Regardless of the specific mechanics of the bottleneck, we know what the proximate source of the problem is: openai locking up 40% of Samsung and SK Hynix wafer capacity for the next few years. That's what triggered the madness.

Is there an understanding of what OpenAI intends to do with that memory?

Surely they need GPU capacity and would need memory for those GPUs but OpenAI doesn't build GPUs or any hardware, right? So did they pay to keep the supply locked up, or do they have the ability to put that ram into use?

I guess they could have a thousand GPU's each generate the next 20 microseconds in computer games, and play at 50 kHz frame rates, in order to truly eliminate motion blur regardless of what in game object motion your eyes are tracking.

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