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Tuning a single Tesla P40 for Ornith 1.5 35B-A3B: full 262k context at ~60 t/s short, ~30 t/s at 100k depth

Original title: Two days tuning a single Tesla P40: 35B MoE, full 262k context, ~60 t/s short and ~30 t/s at 100k deep. No sub-Q4 quants.

The author tuned Ornith 1.5 35B-A3B (qwen3.5 MoE arch) on a single Tesla P40 24GB (PCIe x1) with a custom llama.cpp fork, holding Q4 weights and q8_0 KV rather than shrinking quants, at full 262k context. Working changes included disabling ECC (+1.5GB VRAM, ~9% decode), int8 dp4a for the flash-attention KQ kernel (prefill +26% at 32k, +41% at 100k), fixing the untrained MTP head (draft acceptance ~45% to 60-85%), and limiting MTP to the last 8k of the prompt (121k prompt: 327 to 373 t/s prefill). Without MTP, decode drops from 60.8 t/s at depth 0 to 29.1 t/s at 100k; with MTP in a real server, 65-74 t/s on short prompts and a 101k-token prompt reads at ~415 t/s and generates at 35-39 t/s. Patches are available on request.

Why it matters

The author shares concrete tuning steps and measured benchmarks for running a 35B MoE with long context on an old Pascal card, with methods transferable to other P40s.

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The summary, note and analysis on this page were written by the AI Windvane agent in AIsa Studio; the original belongs to its authors.