Ornith-1.5-35B-A3B GPTQ-Int4 G128 MixedCal-v2 (MTP BF16)

Self-reported Intel Arc Pro B70 measurements (E2) with raw evidence. Isolated C1, cache off, greedy diagnostic. Not independently reproduced. LocalMaxxing payloads are validate-local only and not submitted.

Local GPTQ INT4 conversion of ornith-ai/Ornith-1.5-35B-A3B for Intel Arc Pro B70 / vLLM XPU. This is not an official Ornith GPTQ.

What changed vs the first conversion

The first B70 GPTQ (Ornith-1.5-35B-A3B-GPTQ-Int4-sym-G128-MTP-BF16) used WikiText-style calibration. GPTQModel fell back to round-to-nearest on 7,605 / 30,720 = 24.76% of expert projection matrices (layer 39: 297/768).

MixedCal-v2 keeps the same format and tensor scope and only changes calibration coverage:

RTN fallback is a quantizer weight-only fallback, not a runtime CPU/XPU kernel fallback. The tensors remain GPTQ INT4.

Held-out no-spec quality A/B vs the original: both artifacts produced coherent answers on the six diagnostic domains. No BF16 logit/KL or task-suite score is claimed.

Speed on vLLM XPU at 150 W, C1, cache off, n=5 confirmation: parity (instance-median of three loads):

Do not call this artifact “faster.” The conversion win is calibration coverage and fewer RTN fallbacks.

Quantization contract (fail-closed)

Quantized:

• model.language_model.layers.*.mlp.experts.{gate,up,down}_proj

Not quantized:

• lm_head, embeddings
• attention / GDN
• router (mlp.gate)
• shared experts
• entire mtp.* tree (draft stays BF16 on disk)
• vision tower

dynamic = {
    "-:.*attn.*": {},
    "-:.*mlp\\.gate$": {},
    "-:.*mtp.*": {},
    "-:.*shared_expert.*": {},
    "-:.*visual.*": {},
    "lm_head": {},
    "model.language_model.embed_tokens": {},
}

Quantizer: GPTQModel 7.3.2. Source revision fbb995a79eedd569a5edc5f2af9644c0fa1124fc. Conversion wall ~7.7 h on B70 inside vllm/vllm-openai-xpu@sha256:f01e24f6….

Serve on Intel Arc Pro B70

Pinned image (same digest as the Qwen3.8-27B nightly path, not the historical v0.21 native-int4moe image):

vllm/vllm-openai-xpu@sha256:f01e24f6c7ff01f1e0662234255a1372297d1dbd89d003cf13c8fad3eab1ba4f
vLLM 0.27.2rc1.dev77+gac7509e2b
vllm-xpu-kernels 0.1.12.3
MoE backend observed: XPU WNA16 (int_wna16)

Research default is MTP1, not MTP4. This head is a single MTP layer; acceptance past pos0 collapses (day-0 per-pos 81 / 15 / 2.5 / 0.5%).

vllm serve /model \
  --quantization gptq --dtype float16 \
  --max-model-len 16384 --gpu-memory-utilization 0.85 \
  --kv-cache-dtype auto --block-size 64 \
  --max-num-seqs 8 --max-num-batched-tokens 8192 \
  --no-enable-prefix-caching --language-model-only --trust-remote-code \
  --speculative-config '{"method":"mtp","num_speculative_tokens":1}'

Vision serving (full VLM)

The 333-tensor vision tower ships unquantized BF16 (~0.89 GB) in this artifact — same exclusion scope as the MTP heads (see the quantization contract above). Serve image inputs by dropping --language-model-only; everything else stays identical (MTP1, same image digest, same patches).

VRAM note (fp8 KV, --gpu-memory-utilization 0.90, MTP1): the tower plus multimodal profiling take ~0.9 GiB from the KV budget, so --max-model-len 160000 fails the startup KV check (1.82 GiB needed, 1.77 GiB available; vLLM estimates a 154,176 maximum). Use --max-model-len 131072 (~1.49 GiB needed) or raise --gpu-memory-utilization.

Verified 2026-08-23 on the identically-scoped AutoRound twin artifact (same packing, same 333 BF16 visual + 785 BF16 MTP tensors): a 64×64 red-PNG request returns red with ~78 image prompt tokens; text-only requests unchanged. Step-by-step: ORNITH-VLLM-XPU.md §3b.

Measured C1, cache off (client SSE)

Cold input = actual endpoint prompt tokens / client TTFT, not llama-bench pp.

Paired A/B on one warm MixedCal-v2 no-spec 32K server, three alternating rounds, matched except configured cap. 230 W recovers the day-0 ~9.5–9.7k class. After a 230→150 drop the first retained p2048 sample is ~8.7k before later samples settle ~6.9k; do not treat that first sample as 150 W sustained.

LocalMaxxing long-prompt no-spec 32K @230 W (unique entropy, actual 2,899 prompt tokens, --max-tokens 1, n=5): tokSPrefill 9556.4. Same-load HTTP harness medians: p2048/g1 9428 (n=4 valid TTFT), p8192/g1 9608 (n=5). Prefix-cache hit delta 0. validate-local valid. Not submitted. Do not publish LMX tokSOut from a 1-token completion.

Optional local DraftINT4 overlay (B70_DRAFT_LMHEAD_INT4 + B70_DRAFT_MTP_INT4) does not change these weight files. On this image, MTP1 DraftINT4 n=5 screened 106.27 / 97.16 tok/s vs BF16-draft 96.43 / 89.85, accept 81.9% vs 77.0%. Overlay is optional and local-only.

Exact 131,072-token MTP completions need patch_mtp_boundary.py. A 262,144 no-spec serve is a capacity completion, not a quality claim.

Recipe: intel-arc-pro-b70-inference-cookbook docs/ornith15-35a3/.

What this is not

• Not a drop-in for Qwen3.6-35B MTP4 204.6 tok/s (that cell is a different image generation: vLLM 0.21 native int4moe + int8 store, short g32).
• Not DFlash2. No Ornith DFlash2 draft is published; the Arc Pro DFlash2 write-up is SGLang / Qwen3.8-27B.
• Not a LocalMaxxing submission unless a later record says otherwise.

License

Follow the Ornith-1.5 source license (Apache-2.0 on the recorded card) plus any additional terms of ornith-ai/Ornith-1.5-35B-A3B.