Independent test finds GPT-6.1 Sol nears Astra without chain-of-thought
A single researcher's rerun shows the new Sol release closing most of the no-CoT gap to Astra; the architecture explanation remains his own guess.
Researcher Rauno Arike reports on LessWrong that GPT-6.1 Sol, without chain-of-thought, closes 80% of the gap between GPT-6 Sol and GPT-6 Astra across 27 tasks (95% CI: 72–87%), and sits closer to Astra than to GPT-6 Sol on 24 of 27.
The run follows his earlier no-CoT evaluation of Astra: since 6.1 Sol does not support disabling reasoning, he substituted reasoning_effort=low with an immediate-recall system prompt, took k=1 sample per question, and excluded nine tasks that previously failed to separate the older models. Time-horizon estimates moved from 4.0 minutes for GPT-6 Sol to 35 minutes, though the author himself flags that most benchmarks saturate, making those estimates highly uncertain.
His looped-transformer explanation rests on a gpt-6-astra-minor registry path spotted in Azure's playground configuration and community speculation; OpenAI has not confirmed it.
Sources:https://www.lesswrong.com/posts/LqSZZAriGqgsGDQe3/gpt-6-1-sol-nearly-matches-the-no-cot-performance-of-gpt-6https://techcrunch.com/2026/09/29/openai-launches-gpt-6-1-sol-says-it-nearly-matches-gpt-6-astra-and-costs-less