OpenAI previews Ultrafast mode for GPT-5.6 Sol via Cerebras

OpenAI previewed Ultrafast mode on August 13, a new GPT-5.6 Sol service tier powered by Cerebras' wafer-scale chips that runs at up to 750 output tokens per second, about 14 times faster than standard processing, at the same intelligence level as the standard model. OpenAI said Ultrafast completed the 2,500-question Humanity's Last Exam benchmark in just over 11 hours versus several days of continuous compute on standard hardware, and it is launching in limited preview to a small group of API customers with access expanding as capacity grows.