OpenAI is releasing new generative AI models today, and no, GPT-5 is not one of them. Depending on how you feel about generative AI, these new models may be even more interesting, though. The company is rolling out gpt-oss-120b and gpt-oss-20b, its first open-weight models since the release of GPT-2 in 2019. You can download and run these models on your own hardware, with support for simulated reasoning, tool use, and deep customization.
When you access the company’s proprietary models in the cloud, they’re running on powerful server infrastructure that cannot be replicated easily, even in enterprise. The new OpenAI models come in two variants (120b and 20b) to run on less powerful hardware configurations. Both are transformers with a configurable chain of thought (CoT), supporting low, medium, and high settings. The lower settings are faster and use fewer compute resources, but the outputs are better with the highest setting. You can set the CoT level with a single line in the system prompt.
The smaller gpt-oss-20b has a total of 21 billion parameters, utilizing mixture-of-experts (MoE) to reduce that to 3.6 billion parameters per token. As for gpt-oss-120b, its 117 billion parameters come down to 5.1 billion per token with MoE. The company says the smaller model can run on a consumer-level machine with 16GB or more of memory. To run gpt-oss-120b, you need 80GB of memory, which is more than you’re likely to find in the average consumer machine. It should fit on a single AI accelerator GPU like the Nvidia H100, though. Both models have a context window of 128,000 tokens.
The team says users of gpt-oss can expect robust performance similar to its leading cloud-based models. The larger one benchmarks between the o3 and o4-mini proprietary models in most tests, with the smaller version running just a little behind. It gets closest in math and coding tasks. In the knowledge-based Humanity’s Last Exam, o3 is far out in front with 24.9 percent (with tools), while gpt-oss-120b only manages 19 percent. For comparison, Google’s leading Gemini Deep Think hits 34.8 percent in that test.