The article discusses how local implementations of large language models (LLMs) can feel less intelligent than their reference implementations due to differences in hardware and software. It presents experiments to measure the impact of implementation-specific hazards on inference, including the effects of attention backends, KV cache quantization, and weight quantization. The results show significant divergence in token probabilities and top-1 agreement between different backends and quantization methods. This divergence can lead to errors and inconsistencies in the model's output.