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

== gpt-5-1-thinking ==
=== User: Compare this approach with mi450x to standard llama 3 400b training on vr 200 Rubin ===
Compare this approach with mi450x to standard llama 3 400b training on vr 200 Rubin

=== Assistant: Short version: ===
Short version:
* Zebra-Llama on MI450X = “cheap, fast post-training on smaller hybrids”.
* Llama-3 400B on Rubin VR-200 = “insanely expensive frontier pre-training run”.

They live in almost different economic universes.

==== ### ====
* Zebra-Llama / AMD-HybridLM = post-trained hybrid models (1B–8B so far) that: - Start from a pre-trained Transformer (e.g. Llama-style). - Replace many Transformer blocks with MLA + Mamba2 SSM layers. - Use 7–11B tokens of post-training instead of trillions. arXiv<ref>{{cite web|title=arXiv|url=https://arxiv.org/html/2505.17272v1|publisher=arxiv.org|access-date=2025-11-16}}</ref>
* AMD’s HybridLM blog shows e.g. a 1B hybrid trained on 7B tokens in ~17 hours on 8× MI300 → 136 GPU-hours; similar variants with 10B tokens take ~30 hours (~240 GPU-hours). ROCm Blog<ref>{{cite web|title=ROCm Blog|url=https://rocm.blogs.amd.com/artificial-intelligence/hybrid-models%2C-mla%2C/README.html|publisher=ROCm Blog|access-date=2025-11-16}}</ref>
* Goal: keep accuracy close to the base model while: - Slashing KV-cache by 10–30×. - Improving long-context throughput. - Cutting post-training cost by ~3–4 orders of magnitude vs pre-training.

Now imagine doing that on MI450X instead of MI300:
* Helios racks: up to 72 MI450X per rack, 432 GB HBM4 per GPU, ~1.4 EF FP8 per rack, 31 TB HBM total. Tom's Hardware<ref>{{cite web|title=Tom's Hardware|url=https://www.tomshardware.com/tech-industry/amd-debuts-helios-rack-scale-ai-hardware-platform-at-ocp-global-summit-2025-promises-easier-serviceability-and-50-percent-more-memory-than-nvidias-vera-rubin|publisher=Tom's Hardware|access-date=2025-11-16}}</ref>
* Same post-training recipe basically ports over: 8–16 MI450X nodes chew through 7–11B token runs very quickly, with even better perf/W than MI300.

===== - Meta reports Llama-3.1 405B was trained on 15T+ tokens, using 39.3M H100-80GB GPU-hours (700 W TDP class). Meta AI<ref>{{cite web|title=Meta AI|url=https://ai.meta.com/blog/meta-llama-3-1/|publisher=Meta AI|access-date=2025-11-16}}</ref> =====
* Architecture: vanilla giant decoder-only Transformer (no MoE), extended context, etc. datacamp.com<ref>{{cite web|title=datacamp.com|url=https://www.datacamp.com/blog/llama-3-1-405b-meta-ai|publisher=datacamp.com|access-date=2025-11-16}}</ref>
* Rubin VR-200 is Nvidia’s next-gen data-center training GPU in the Rubin family: - Positioned as the workhorse training GPU alongside Rubin CPX (long-context prefill) and R100 decode parts. Futurum<ref>{{cite web|title=Futurum|url=https://futurumgroup.com/insights/nvidias-new-rubin-cpx-targets-future-of-large-scale-inference/|publisher=futurumgroup.com|access-date=2025-11-16}}</ref> - VR-200-based platforms (e.g. NVL144 / Rubin + Vera racks) are targeted at multi-exaflop FP4/FP8 training/inference with extreme rack-level power (approaching 1 MW racks). NVIDIA Newsroom<ref>{{cite web|title=NVIDIA Newsroom|url=https://nvidianews.nvidia.com/news/nvidia-unveils-rubin-cpx-a-new-class-of-gpu-designed-for-massive-context-inference|publisher=NVIDIA Newsroom|access-date=2025-11-16}}</ref>
* Exact per-GPU TFLOPs for VR-200 aren’t public yet; safe assumption is significantly above Blackwell GB200 and well above H100.

So the “standard Llama-3 400B on Rubin” scenario is:

: 

==== ### ====
* Llama-3.1 405B: ~15T tokens. Meta AI<ref>{{cite web|title=Meta AI|url=https://ai.meta.com/blog/meta-llama-3-1/|publisher=Meta AI|access-date=2025-11-16}}</ref>
* Zebra-Llama / HybridLM: 7–11B tokens for 1–8B hybrids. arXiv<ref>{{cite web|title=arXiv|url=https://arxiv.org/html/2505.17272v1|publisher=arxiv.org|access-date=2025-11-16}}</ref>

Token ratio:

15×101210×109≈1500×\frac{15 \times 10^{12}}{10 \times 10^{9}} \approx 1500\times10×10915×1012≈1500×
So just on tokens, the full 400B pre-train is ~1.5–2.0k× heavier than a single 8B hybrid post-train.

===== Concrete known number: =====
* Llama-3.1 405B: 39.3M H100 GPU-hours. Hugging Face<ref>{{cite web|title=Hugging Face|url=https://huggingface.co/meta-llama/Llama-3.1-405B|publisher=Hugging Face|access-date=2025-11-16}}</ref>

For hybrids, we have actual MI300 data:
* 1B hybrid, 7B tokens: 136 MI300 GPU-hours. ROCm Blog<ref>{{cite web|title=ROCm Blog|url=https://rocm.blogs.amd.com/artificial-intelligence/hybrid-models%2C-mla%2C/README.html|publisher=ROCm Blog|access-date=2025-11-16}}</ref>

If you roughly scale that up to an 8B hybrid on similar hardware:
* 8× parameters → ~8× compute.
* 7B → 11B tokens → ~1.6×.

So ballpark:

136×8×1.6≈1,700 GPU-hours136 \times 8 \times 1.6 \approx 1{,}700 \text{ GPU-hours}136×8×1.6≈1,700 GPU-hours
Call it ~1–3k GPU-hours for an 8B hybrid.

GPU-hour ratio (H100 vs MI-class is apples/oranges, but order-of-magnitude still works):

39.3 M1.7 k≈23,000×\frac{39.3\text{ M}}{1.7\text{ k}} \approx 23{,}000\times1.7 k39.3 M≈23,000×
So one 8B Zebra-Llama-style hybrid is ~10⁴–10⁵× cheaper in GPU-hours than a 400B pre-train.

Even if Rubin VR-200 is, say, 3–4× faster than H100 for training, you’re still looking at several million VR-200 GPU-hours for the 400B run vs thousands of MI450X GPU-hours for a hybrid.

==== ### ====

From AMD’s OCP Helios disclosure: Tom's Hardware<ref>{{cite web|title=Tom's Hardware|url=https://www.tomshardware.com/tech-industry/amd-debuts-helios-rack-scale-ai-hardware-platform-at-ocp-global-summit-2025-promises-easier-serviceability-and-50-percent-more-memory-than-nvidias-vera-rubin|publisher=Tom's Hardware|access-date=2025-11-16}}</ref>
* Per rack: - 72 × MI450. - ~1.4 EF FP8. - 31 TB HBM4 (432 GB / GPU).
* Rack powers in the 600–900 kW class are implied by that performance + HBM4 + CPUs/NICs (exact TDPs are not yet public, but we know this is “near 1 MW rack” territory for both AMD & Nvidia).

Given how light the hybrid post-training is, a few Helios racks can:
* Train dozens to hundreds of 1–8B hybrids (per week/month).
* Run SFT + distillation on domain-specific data.
* Still have most of their duty cycle available for inference / serving.

===== From Nvidia’s Rubin coverage: =====
* Rubin racks (e.g. Vera Rubin NVL144 CPX) pack 144 main Rubin GPUs + 144 Rubin CPX GPUs + Vera CPUs, hitting 8 EF NVFP4 and 100 TB “fast memory” per rack. NVIDIA Newsroom<ref>{{cite web|title=NVIDIA Newsroom|url=https://nvidianews.nvidia.com/news/nvidia-unveils-rubin-cpx-a-new-class-of-gpu-designed-for-massive-context-inference|publisher=NVIDIA Newsroom|access-date=2025-11-16}}</ref>
* Designed explicitly for million-token contexts, huge PFLOPs, and are expected to land in the ~1 MW per rack regime.

A full 400B pre-train on Rubin VR-200 would:
* Run across thousands to tens of thousands of GPUs.
* Consume many GWh of energy over the run.
* Occupy a non-trivial fraction of a Rubin “AI factory” for weeks.

By contrast, the hybrid MI450X runs are rounding errors in power and time at that scale.

==== This is the core “is it worth it?” question. ====

===== Pros: =====
* Peak capability: 400B dense Transformer gives you: - Better long-tail reasoning. - Higher knowledge capacity. - Better few-shot / zero-shot across obscure edge cases.
* Single foundation: One massive model that you can: - Fine-tune. - Distill into smaller students (including hybrids like Zebra-Llama).
* Rubin stack: VR-200 + CPX + Kyber interconnect are optimized for: - NVFP4 / FP8 training. - Disaggregated prefill/decode. - Huge context inference at massive scale. NVIDIA Newsroom<ref>{{cite web|title=NVIDIA Newsroom|url=https://nvidianews.nvidia.com/news/nvidia-unveils-rubin-cpx-a-new-class-of-gpu-designed-for-massive-context-inference|publisher=NVIDIA Newsroom|access-date=2025-11-16}}</ref>

Cons:
* Capex + opex are astronomical.
* Ultra high power density / cooling requirements (1 MW-class racks).
* You only do this for a handful of foundation models globally.

===== Pros: =====
* Training cost: - 1–2 orders of magnitude fewer tokens. - ~10⁴× less GPU-compute vs 400B pre-train.
* Inference efficiency: - KV-cache shrunk by 10–30× → dramatically better tokens/W and memory/W for long context. arXiv<ref>{{cite web|title=arXiv|url=https://arxiv.org/html/2505.17272v1|publisher=arxiv.org|access-date=2025-11-16}}</ref> - Fits nicely with MI450X’s huge 432 GB HBM4 per GPU; you can hold many concurrent sequences or long contexts per device.
* Deployment flexibility: - Easy to spin up per-customer / per-workload models. - Post-training cycles measured in hours–days, not weeks. - You can saturate Helios racks with hundreds of such jobs over time.

Cons:
* You’re capped at 1–8B (today) – far below 400B.
* Quality is bounded by: - The teacher’s capabilities. - The hybridization & distillation quality.
* For frontier-level reasoning / generality, they complement but don’t entirely replace a 400B class foundation.

==== If you imagine a 1 GW AI factory, you’d use these two very differently: ====

===== - Train a small number of frontier 400B-class models. =====
* This is like building one super-refinery: huge, rare, insanely capital intensive.
* Its output (weights / logits) can be: - Served directly for premium workloads. - Used to distill and post-train many smaller models elsewhere.

===== - Take the already-trained 400B teacher (maybe trained on Rubin, maybe externally). =====
* On MI450X, do: - Zebra-Llama-style post-training → 1–8B hybrids tuned for: - Lower KV cache. - Better long-context efficiency. - Specific domains (code, finance, internal docs, etc.). - SFT, RAG-alignment, safety tuning.
* Economically: - For the power and cost of one 400B Rubin pre-train, you can train thousands of hybrids on MI450X. - That lets you match models to workloads and chase tokens-per-dollar instead of “biggest possible model at all times”.

==== Comparing “Zebra-Llama on MI450X” vs “standard Llama-3 400B on Rubin VR-200”: ====
* Training scale: - VR-200 + 400B Llama-3 = 15T-token, 10⁷–10⁸ GPU-hour endeavor. - MI450X + Zebra-Llama-style hybrid = 10¹⁰-token, 10³-GPU-hour endeavor. → The hybrid route is ~10⁴× cheaper in GPU-hours per model.
* Hardware fit: - Rubin VR-200 is overkill for hybrids; it shines on frontier pre-training. - MI450X Helios is almost perfect for post-training lots of small/medium models and serving them, especially with huge HBM4 capacity and ROCm-tuned hybrid kernels.
* Economic role: - You justify Rubin VR-200 only if you’re in the business of creating new frontier foundations. - You justify MI450X + Zebra-Llama if you want to exploit those foundations at scale, cheaply, and with workload-specific tuning.

If you want, next step we can numerically budget:
* “How many Zebra-Llama-8B hybrids can I post-train per year on a 1 GW MI450X site?” vs
* “How many Llama-3-400B-class pre-trains can I run per year on a 1 GW Rubin VR-200 site?”

…and turn that into a tokens-per-year / dollars-per-model comparison.

=== User: Break down the cost equivalency in dollars to train collection of models ===
Break down the cost equivalency in dollars to train collection of models

=== Assistant: Cool, let’s put actual dollar signs on this. ===
Cool, let’s put actual dollar signs on this.

I’ll do:
# Cost to train a Llama-3.1-class 405B model (Meta’s run)
# Cost to train an 8B Zebra-Llama-style hybrid
# “Collection of models” equivalence: how many hybrids you get for one 400B run

I’ll be explicit about assumptions so you can swap your own numbers.

==== 1. Cost of a 400B Llama-3-style pre-train (H100 → Rubin VR-200) ====

===== 1.1 Compute volume =====

Meta reports for Llama-3.1: Hugging Face<ref>{{cite web|title=Hugging Face|url=https://huggingface.co/blog/llama31|publisher=Hugging Face|access-date=2025-11-16}}</ref>
* Total for all 3 models: 39.3M H100-80GB GPU-hours
* Of that, the 405B model used ≈ 30.84M GPU-hours

I’ll use 30.84M GPU-hours as the 400B pre-train cost.

Rubin VR-200 should be faster than H100, but you still need essentially the same total FLOPs. If VR-200 is, say, ~2× faster than H100, you might cut this to ~15M GPU-hours, but I’ll keep the 30.8M number as an H100-equivalent so it’s easy to scale.

===== 1.2 $/GPU-hour assumptions =====

Public cloud H100 on-demand ballpark (late 2025):
* Thundercompute & similar trackers show H100 at roughly $1.9–$6/GPU-hr depending on provider and commitment. Thunder Compute<ref>{{cite web|title=Thunder Compute|url=https://www.thundercompute.com/blog/nvidia-h100-pricing|publisher=Thunder Compute|access-date=2025-11-16}}</ref>
* Other guides show typical on-demand around $3–$6/GPU-hr. Jarvis Labs Docs<ref>{{cite web|title=Jarvis Labs Docs|url=https://docs.jarvislabs.ai/blog/h100-price|publisher=Jarvis Labs Docs|access-date=2025-11-16}}</ref>

For a big hyperscaler, effective cost per GPU-hr is lower than list price if you own hardware, but you’re then amortizing capex instead. Using cloud-style numbers gives you a clean upper bound.

Let’s bracket it with:
* Low: $3 / GPU-hr (big buyer / efficient own hardware equivalent)
* High: $6 / GPU-hr (retail-ish cloud)

===== 1.3 Direct compute $ for the 400B run =====

GPU cost:
* Low: 30.84M hr×$3/hr≈$92.5M30.84\text{M hr} \times \$3/\text{hr} \approx \$92.5\text{M}30.84M hr×$3/hr≈$92.5M
* High: 30.84M hr×$6/hr≈$185M30.84\text{M hr} \times \$6/\text{hr} \approx \$185\text{M}30.84M hr×$6/hr≈$185M

So call it ~$100–$200M of GPU time to pre-train one Llama-3-class 400B dense model if you priced it at current H100 cloud economics.

===== 1.4 Power cost (just to sanity-check scale) =====

H100-80GB TDP is ~700 W. Google Cloud<ref>{{cite web|title=Google Cloud|url=https://console.cloud.google.com/vertex-ai/publishers/meta/model-garden/llama-3.1-405b-instruct-maas?hl=de|publisher=Google Cloud|access-date=2025-11-16}}</ref>

Energy used:

30.84M hr×0.7 kW=21.6M kWh30.84\text{M hr} \times 0.7\text{ kW} = 21.6\text{M kWh}30.84M hr×0.7 kW=21.6M kWh
Average US all-sector electricity price ≈ 13–14¢/kWh in mid-2020s. AAF<ref>{{cite web|title=AAF|url=https://www.americanactionforum.org/insight/how-much-are-electricity-prices-rising-and-why/|publisher=americanactionforum.org|access-date=2025-11-16}}</ref>

Power cost range:
* At $0.12/kWh → ≈ $2.6M
* At $0.16/kWh → ≈ $3.5M

So energy is a few million, dwarfed by GPU capex/rental, but non-trivial.

: Takeaway: One Llama-3.1-405B-class pre-train is on the order of
: $100–$200M (compute), plus $3–$5M of energy, plus infra/engineering.

Rubin VR-200 just changes the constant factor (fewer GPU-hrs at higher $/GPU-hr), but you’re still very solidly in the nine-figure ballpark for a frontier 400B run.

==== 2. Cost of a Zebra-Llama-style 8B hybrid on MI450X ====

Now compare that to post-training a hybrid (1–8B) starting from an existing foundation.

===== 2.1 GPU-hours for a hybrid =====

AMD HybridLM / Zebra-Llama prototypes report: ROCm Blog<ref>{{cite web|title=ROCm Blog|url=https://rocm.blogs.amd.com/artificial-intelligence/hybrid-models%2C-mla%2C/README.html|publisher=ROCm Blog|access-date=2025-11-16}}</ref>
* 1B hybrid (HybridLM), 7B tokens, trained in ~17 hr on 8 × MI300 - That’s 136 GPU-hours.
* Other variants at 10B tokens are in the same order of magnitude (a few hundred GPU-hours).

If we scale that to an 8B hybrid:
* 8× parameters ⇒ ~8× compute.
* 7B → 11B tokens ⇒ ~1.6×.
* Rough GPU-hr:

136×8×1.6≈1,700 GPU-hours136 \times 8 \times 1.6 \approx 1{,}700 \text{ GPU-hours}136×8×1.6≈1,700 GPU-hours
So a Zebra-Llama-8B-class post-train is probably in the 1–3k GPU-hr range. I’ll use 1,700 GPU-hr as a mid estimate.

===== 2.2 $/GPU-hr for MI450X =====

We don’t have MI450X cloud prices yet, but we do have MI300X:
* MI300X on-demand ranges from $1.5–$3.3 / GPU-hr depending on provider (Vultr, TensorWave, RunPod, etc.). Thunder Compute<ref>{{cite web|title=Thunder Compute|url=https://www.thundercompute.com/blog/amd-mi300x-pricing|publisher=Thunder Compute|access-date=2025-11-16}}</ref>

MI450X will be newer and denser; to be conservative I’ll assume:
* Effective range: $2.5–$3.0 / GPU-hr (similar to “nice” MI300X or discounted H100).

===== 2.3 Cost per 8B hybrid =====

Using 1,700 GPU-hr:
* Low (2.5 $/hr): 1,700×$2.5≈$4,2501{,}700 \times \$2.5 \approx \$4{,}2501,700×$2.5≈$4,250
* High (3.0 $/hr): 1,700×$3.0≈$5,1001{,}700 \times \$3.0 \approx \$5{,}1001,700×$3.0≈$5,100

So one full 8B Zebra-Llama-style post-train is on the order of $4–5k of GPU time.

Power cost: if MI450X is ~1kW while training, then:

1,700 hr×1 kW=1,700 kWh1{,}700\text{ hr} \times 1\text{ kW} = 1{,}700\text{ kWh}1,700 hr×1 kW=1,700 kWh
At $0.14/kWh → $238. So energy is basically noise compared to GPU cost for small models.

: Takeaway: A full 8B hybrid post-train is in the low thousands of dollars in raw compute, not millions.

==== 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.

==== 4. Summary in one sentence ====

At current-ish GPU economics, one Llama-3-class 400B pre-train (on H100/Rubin-equivalent hardware) costs in the ballpark of $100–200M, while a full Zebra-Llama-style 8B post-train on MI450X is only $4–5k, so a single 400B foundation run is roughly equivalent in raw compute dollars to training on the order of ''tens of thousands'' of 8B hybrid models.

If you want, next step we can build a little table:
* rows = “budget” ($10M, $50M, $100M)
* columns = “# 400B runs”, “# 70B runs”, “# 8B hybrids”

and plug in your own $/GPU-hr & power assumptions to stress-test AI-factory ROI.