Editing Openai/69191dd5-6360-800d-b47b-7ebcc8b69dc8 (section)

==== 3. Cost equivalence: one 400B run vs a collection of hybrids ====

Now the fun part: how many 8B hybrids can you train for the cost of one 400B pre-train?

===== 3.1 Direct ratio =====

Using:
* 400B run cost: $92.5–$185M (GPU only)
* 8B hybrid cost: $4.25–$5.1k

Two useful edges:
# Optimistic for the 400B (cheap H100) vs expensive hybrids - Numerator: $92.5M - Denominator: $5.1k → ≈18,000 8B hybrids\approx 18{,}000\ \text{8B hybrids}≈18,000 8B hybrids
# Pessimistic for the 400B (expensive H100) vs cheap hybrids - Numerator: $185M - Denominator: $4.25k → ≈43,000 8B hybrids\approx 43{,}000\ \text{8B hybrids}≈43,000 8B hybrids

So the cost of ''one'' Llama-3-class 400B pre-train roughly buys you:

: ~18k–40k post-trained 8B Zebra-Llama-style models.

Even if my hybrid GPU-hrs estimate is off by a big factor (say 3×), you’re still in the many thousands of hybrids per 400B run.

===== 3.2 Concrete “collection” examples =====

Let’s say you want a fleet of task-/tenant-specific models:

====== Example A – 1,000-model fleet (per-team/per-customer variants) ======
* 1,000 × 8B hybrids × $5k ≈ $5M in GPU time
* That’s: - ~5% of a cheap 400B run (~$100M) - ~2–3% of an expensive 400B run (~$200M)

So one 400B pre-train funds ~20 such 1,000-model fleets.

====== Example B – 100 “premium” hybrids (extra tokens, extra tuning) ======

Even if you triple the cost per hybrid (heavier SFT, RL, eval):
* Per hybrid: ~$15k
* 100 models: $1.5M

Still <2% of a single 400B foundation training cycle.

===== 3.3 How this maps to an AI factory =====

If you have:
* A Rubin VR-200 “foundation plant”: - You swallow $100–$200M to birth one frontier 400B model.
* A MI450X Helios “post-training refinery”: - You spend single-digit millions per year to continuously spin out: - Per-domain hybrids (code, legal, finance, internal docs) - Per-tenant or per-product instances - Experiments (architecture variants, safety variants, tooling variants)

Economically:
* 400B runs are rare, capital-intensive events.
* Post-training hybrids are cheap, repeatable SKUs you can generate by the hundreds or thousands for the same budget.