Cognition factored RSA-260 with 3 to 18 concurrent Devin sessions over three weeks and 4,900 GPU-days
Cognition published on 2026-09-09 that researcher Eric Lu factored RSA-260 into two 130-digit primes using a GPU-optimized General Number Field Sieve implementation built by Devin, beating the RSA-250 record standing since February 2020. The run consumed roughly 4,900 GPU-days (about $400K at market rates) scavenged from fragmented idle nodes in Cognition's NVL72 LLM training racks, with an average of 3 and a peak of 18 concurrent Devin sessions across three weeks. The honest part of the writeup is the human cost: Lu wrote 82,000+ words across 3,328 messages steering Devin, and says the unified benchmarking framework "was not otherwise going to self-assemble" — the agent did the measurement and cluster work end-to-end, a person supplied the research strategy.
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