CPU, GPU, NPU and TPU - The Real Differences for AI/ML
CPU (Central Processing Unit)
The classic processor in every computer. CPUs can run any software, including AI models, but are slower for deep learning due to fewer parallel cores.
Best for:
- Traditional machine learning (scikit-learn, XGBoost)
- Running small models or prototypes
- General-purpose tasks and light inference
GPU (Graphics Processing Unit)
GPUs are built for parallel processing. They are the backbone of modern deep learning, perfect for training and inference of models like CNNs, RNNs, and transformers (GPT, BERT, ResNet).
Best for:
- Training and running large deep learning models
- Supported by all major AI libraries
- Flexible for many AI workloads
NPU (Neural Processing Unit)
NPUs are specialised chips designed only for neural network operations, often embedded in smartphones and IoT devices. They run efficient models for vision, speech, and edge AI.
Best for:
- On-device, real-time AI (face unlock, language translation)
- Battery-friendly AI in mobile and IoT
- Lightweight, efficient models
TPU (Tensor Processing Unit)
TPUs are Google’s custom AI accelerators, tuned for TensorFlow and massive neural networks. Ideal for training and deploying large models at cloud scale.
Best for:
- Scalable deep learning in Google Cloud
- Training and inference for big models (BERT, GPT-2, EfficientNet)
- High-speed tensor calculations
Which AI models run on each?
CPU: Any model, but best for classical ML, prototyping, and small-scale inference
GPU: All deep learning models (CNNs, RNNs, transformers)
NPU: Optimised mobile and edge models (MobileNet, tiny BERT)
TPU: Large-scale neural networks in TensorFlow
Note DPUs (Data Processing Units):
DPUs don’t run AI models directly, but they play a key role in modern AI infrastructure. They accelerate data movement, networking, and storage, freeing up CPUs and GPUs for computation making large-scale AI systems faster and more efficient.