Qwen3.6-27B Quantized Models Unstable in Agentic Loops on RTX PRO 6000

vanbukin · reddit · 2026-07-07

Testing Qwen3.6-27B on an RTX PRO 6000 Blackwell (450W) revealed severe reliability issues with NVFP4/FP8 quantized versions during agentic loop tasks, whereas the BF16 version functioned perfectly. The inference stack used was vLLM 0.24.0 + CUDA 13.0 with MTP speculative decoding and prefix caching enabled. The user is investigating whether this is a configuration error or an inherent limitation of quantization for agentic workflows, sharing environment variables and startup commands for community diagnosis.

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