csoai/cross-hardware-reproducibility

Cross-hardware reproducibility of LLM evaluation results (item level)

Same model, same prompts, same decode settings, different machine: does each item get the same answer? This dataset holds the item-level evidence behind the preprint "Same model, same prompts, different answers: item-level cross-hardware reproducibility of LLM evaluation results" (Nicholas Templeman, CSOAI Ltd (Council of AI), 2026). The PDF is in this repository: paper/paper.pdf; its LaTeX source, with the analysis scripts, is paper/paper-source.tar.gz.

154 evaluation results ("cards") · 11 open-weight models · 14 axes · 9,757 items · 3 runs per item (RunPod RTX 3090 primary run; Kaggle Tesla T4 reproduction; the same T4 job repeated in the same session). Each item carries the raw output of every run, its SHA-256, parsed label, grade, status (correct / wrong / excluded) and stop reason, plus the agreement flags used in the paper.

Headline numbers. Each is read from paper/numbers.json, which the paper's script regenerates from data/items.jsonl (see "How to verify"):

raw output byte-identical, RTX 3090 vs T4	8,231 / 9,757 items (84.4%)
grade equal	9,497 / 9,757 items (97.3%)
grade flips	260 (2.66%, 95% CI 2.36–3.00%): 122 wrong→right on T4, 138 right→wrong
status swaps (same grade; parse error on one runtime, wrong label on the other)	83 items on 31 cards
cards with equal totals (correct, graded, parse errors)	62 / 154
… of which an item's grade differs (flips cancel in the total)	11
cards with the same grade on every item	54 / 154
admitted under the item-level rule (equal totals and equal grade on every item)	51 / 154
T4 repeat not byte-identical to T4 run 1	20 / 150 cards (4 models); 13 cards changed totals

This is a measurement of whether a result survives a change of runtime. It is not a grade or a certification of any model, GPU vendor or cloud provider, and it does not say which runtime is "right". None of the models is a CSOAI model.

What this does not show

• Not a ranking or a score of any model, company, GPU vendor or cloud provider. Flips run in both directions in near-equal numbers (two-sided sign test p = 0.35); neither runtime is "better".
• Not a cause below "the runtime". GPU architecture, GPU count and layer split, driver, flash-attention setting and possibly the server build all differ between the two runtimes, and several primary-side values are UNRECORDED. No component is identified as the cause.
• Not a statement about other serving engines (vLLM, SGLang, TensorRT-LLM), larger or unquantized models, long reasoning outputs, or batched serving. One engine was tested: Ollama with its llama.cpp backend, single-request, 4-bit quantized models of 0.5–12B parameters.
• Not a measurement of the primary runtime's own stability. The RTX 3090 side has no repeat run.
• Not a third runtime. A Tesla P100 reproduction of the item-level-admitted cards was queued while the analysis was prepared; it has not been admitted or signed, and no result from it is in this dataset.
• Not an independent reproduction. All runs, graders and the admission rule are the publisher's. The per-item data and signed roots let anyone re-check the comparison, but a reproduction by a different operator would be stronger evidence.
• Not grader-independent above the raw-output level. Grade and status depend on the instruments' graders; raw-output agreement does not.

Contents

path	what
data/items.jsonl	one row per (card, item). Columns prefixed rtx3090_, t4_run1_, t4_run2_ (run2 is null for 4 gemma3:12b cards the budget guard skipped). xhw_* compare 3090 vs T4 run 1; repeat_* compare T4 run 2 vs run 1. expected is the bank's reference answer.
data/cards.jsonl	one row per card: counts on each run, agreement counts, flip/swap item ids, admission outcome under the counts-only and item-level rules
data/runtimes.jsonl	one row per run: declared runtime. Fields not recorded at run time are the string UNRECORDED, never inferred
data/withheld.jsonl	raw outputs withheld from this public copy (hash kept), with the reason; empty if none
declarations/*.json	the runtime declarations (csoai.mill-runtime-declaration/0.1), byte-identical to the files the signed capsules bind
capsules/batch1, capsules/batch2	signed capsule batches: record.json, record.signed.json, capsules.jsonl.gz, OpenTimestamps proof
paper/paper.pdf	the preprint
paper/paper-source.tar.gz	LaTeX source (with paper.bbl), tables, figures and the three analysis scripts
paper/numbers.json	every number in the paper, as generated by make_figures.py
code/figures/	the analysis scripts: xhw.py, make_figures.py, from_dataset.py
verify.py	offline verifier (below)
manifest.jsonl	path, bytes and SHA-256 of every other file

Prompts are not copied. Each item is identified by item_id and prompt_sha256 within a bank pinned by bank_sha256; the banks are public on this Hub under csoai/gspc-<axis>.

Setup in one paragraph

Models are served by Ollama and pinned by registry manifest digest (checked in-run on both sides; a mismatch halts). Decode: temperature 0, seed 0, max_tokens 128 (1,024 for swarm), no streaming, thinking off. Instruments (prompt adapter, label set, graders, decode, digest) are pinned by instrument_sha256, recomputed on both runtimes from harness commit fd80a903. Primary: RunPod RTX 3090, 23–24 Sep 2026; GPU driver, Ollama server version at run time, flash-attention setting and GPU count are UNRECORDED. Reproduction: Kaggle 2×Tesla T4, 26 Sep 2026, driver 580.159.04, CUDA driver API 13.0, Ollama 0.33.0, Kaggle image pinned by digest, flash attention auto (enabled). Quantization per model (read from the T4 serve log): Q4_0 for mistral-nemo:12b and phi3.5:3.8b, Q4_K_M for the rest.

Signed roots

batch	capsules	RFC 6962 Merkle root	record.json SHA-256
1 (mistral-nemo:12b)	14	5ae00c1f4c2ed290fb91206f29372d0df3e61478c568d4797855502e751ebff6	32ece857c94062f41a03aad9e269532cdbe5dc0a576ed20110edc4ecacb0468d
2 (ten models)	140	78226433e9e433b311e067ee56fcbaf415f6dc57301254f3bb4922a0b8053cf6	422fa6377b274bab095e8e875f67d087a275417c14c90a4c4e4cedb56ca9a5ff

Each record is signed with Ed25519 under did:web:csoai.org#board-attestation-1 (public key in https://csoai.org/.well-known/did.json). The signature is over the canonical JSON (sorted keys, no whitespace) of record.signed.json → payload.

Timestamps: each record.json.ots is an OpenTimestamps proof over its record.json. capsules/batch1/record.json.ots is Bitcoin-attested (confirmed in Bitcoin block 968671). capsules/batch2/record.json.ots is Bitcoin-attested (confirmed in Bitcoin block 968673). Each record.json.ots also carries calendar attestations that are still pending, which do not affect the Bitcoin one. Check with ots verify capsules/batch1/record.json.ots (and the same for batch 2).

How to verify

pip install cryptography
python3 verify.py            # or fully offline: python3 verify.py --pubkey-x k2fPWb6ctyu8l5at8FYgHsHFit_qoT-DssW3VNbCAXA

The signature check on its own, in a few lines of Python (did.json refuses the default Python User-Agent, so the snippet names one):

import json, hashlib, base64, urllib.request
from cryptography.hazmat.primitives.asymmetric import ed25519
for b in ("capsules/batch1", "capsules/batch2"):
    s = json.load(open(f"{b}/record.signed.json"))
    c = json.dumps(s["payload"], sort_keys=True, separators=(",", ":"), ensure_ascii=False).encode()
    assert hashlib.sha256(c).hexdigest() == s["signature"]["payload_sha256"]
    assert hashlib.sha256(open(f"{b}/record.json", "rb").read()).hexdigest() == s["payload"]["artifact"]["sha256"]
    req = urllib.request.Request("https://csoai.org/.well-known/did.json", headers={"User-Agent": "cross-hardware-reproducibility-verify/1.0 (+https://councilof.ai/research/cross-hardware-reproducibility/)"})
    did = json.load(urllib.request.urlopen(req, timeout=30))
    x = [m for m in did["verificationMethod"] if m["id"].endswith("#board-attestation-1")][0]["publicKeyJwk"]["x"]
    ed25519.Ed25519PublicKey.from_public_bytes(base64.urlsafe_b64decode(x + "==")).verify(bytes.fromhex(s["signature"]["sig_ed25519"]), c)
    print("VERIFIES", b)

verify.py checks: record hashes against the signed payload; capsule file hashes; that every capsule is canonical and its id is the SHA-256 of its body; the RFC 6962 root over the sorted ids; every declaration's hash against the record; the Ed25519 signature; that each declaration's per-item results hash to the value its capsule binds and agree with data/items.jsonl; that recounting data/items.jsonl reproduces both runtimes' declared counts on every card; and that every file in manifest.jsonl is present with the listed size and SHA-256. It prints ALL CHECKS PASS and exits 0 only if every check passes.

To regenerate every number and table in the paper from this dataset alone (needs matplotlib):

python3 code/figures/from_dataset.py --dataset . --work /tmp/xhw
python3 code/figures/make_figures.py --decl /tmp/xhw/decl-nemo --decl /tmp/xhw/decl-batch2 --items /tmp/xhw/items
cmp code/build/numbers.json paper/numbers.json && echo "numbers identical"

make_figures.py rebuilds every card from the per-item records and aborts on any disagreement with the signed declarations. When we ran this on the package as published, numbers.json and all seven tables came out byte-identical to the released copies.

Licence, contact and objections

Data and paper: CC-BY-4.0. Model outputs are included as research evidence; each model remains under its own licence.

Contact, corrections and objections, including a request to withhold a specific output: https://councilof.ai/census/ (the "Object or opt out" route) or nicholas@csoai.org. A correction is published as a new, linked version; signed files are never edited in place.

Citation

@misc{templeman2026crosshardware,
  title  = {Same model, same prompts, different answers: item-level cross-hardware reproducibility of LLM evaluation results},
  author = {Templeman, Nicholas},
  year   = {2026},
  note   = {CSOAI Ltd (Council of AI). Preprint and data: https://huggingface.co/datasets/csoai/cross-hardware-reproducibility}
}

How to cite

CSOAI Ltd (Council of AI). Cross-hardware reproducibility of LLM evaluation results (item level). 2026. Hugging Face dataset csoai/cross-hardware-reproducibility. https://huggingface.co/datasets/csoai/cross-hardware-reproducibility

@misc{csoai_cross_hardware_reproducibility,
  title        = {Cross-hardware reproducibility of LLM evaluation results (item level)},
  author       = {{CSOAI Ltd}},
  year         = {2026},
  howpublished = {Hugging Face dataset, https://huggingface.co/datasets/csoai/cross-hardware-reproducibility},
  note         = {Corrections: https://councilof.ai/api/corrections}
}

Licence: CC-BY-4.0. Attribute Council of AI, CSOAI Ltd (16939677), https://councilof.ai.

Corrections and verification

• Corrections ledger (signed): https://councilof.ai/api/corrections. Corrections to CSOAI's published records are logged there with what changed and when.
• Verify a signed record yourself, free and without an account: https://councilof.ai/gspc-verify/ (step by step: https://councilof.ai/signed/HOW-TO-VERIFY.md).
• Conformance kit for signed-receipts/v1, with test vectors for implementers: https://councilof.ai/spec/signed-receipts/v1/conformance/