Open weights leak which GPU trained them — six Chinese models read as NVIDIA Blackwell

Antique_Atmosphere97 · reddit · 2026-11-13

A forensics writeup exploits PyTorch's cuRAND/Philox weight initialization: the 2,048-threads-per-SM layout determines where each random number lands, and rows training never touches keep initial values, letting you recover the SM count of the initialization GPU. The method matches all 24 models with disclosed hardware (Llama 3.1 = 132 SMs/H100; Nemotron-3 Ultra = 152/GB200) and reproduces 445 rows of DeepSeek-V4-Flash bit-for-bit on a B300. Six recent Chinese models (DeepSeek-V4-Flash/Pro, Kimi K3/K3.1-Pro, MiniMax-M3, Ling-3.1-flash) all read as Blackwell (148/152 SMs) — the author notes this reveals initialization hardware only, not chip location or rule violations. Practical takeaway: publishing a checkpoint leaks your hardware unless you init on CPU (some Qwen3 did) or avoid this layout.

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