StepFun releases Step 5 Preview as open weights with a 1M-token context

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StepFun has released Step 5 Preview as open weights on Hugging Face and ModelScope, in BF16 and FP8 formats. The sparse MoE model has 600B total and 27B active parameters per token, a 1M-token context window, and native text and vision input.

NVIDIA says the model runs at nearly 8K tokens/sec/GPU on GB300 using NVFP4, and points to SGLang, vLLM and NeMo Automodel for deployment and post-training.

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NVIDIA AI

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Congrats to StepFun on Step 5 Preview 🙌 Their largest open weights release.

The 600B MoE model is built to handle agent tasks lasting up to 24 hours.

The model runs at nearly 8K tokens/sec/GPU on NVIDIA GB300 using NVFP4.

NVP4 checkpoint on @huggingface: https://huggingface.co/stepfun-ai/Step-5-Preview-NVFP4

Deploy with @SGL_project - https://docs.sglang.io/cookbook/autoregressive/StepFun/Step-5-Preview or @vLLM - https://recipes.vllm.ai/stepfun-ai/Step-5-Preview

Post-train with NeMo Automodel: https://github.com/NVIDIA-NeMo/Automodel/blob/main/docs/model-coverage/llm/stepfun-ai/step-5-preview.mdx

Run it with NVIDIA NIM using a single command: https://catalog.ngc.nvidia.com/orgs/nim/nvidia/containers/vllm-model-free-nim-experimental/-

Image from @StepFun_ai's post — StepFun@StepFun_ai

Source: NVIDIA AI · x.comPublished Oct 15, 9:33 AM ET · added here 9:41 AM ET

StepFun releases Step 5 Preview as open weights with a 1M-token context

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