CPU vs GPU for Running LLMs Locally

Researchers and developers need to run large language models (LLMs) such as GPT (Generative Pre-trained Transformer) efficiently and quickly. This efficiency heavily depends on the hardware used for training and inference tasks. Central Processing Units (CPUs) and Graphics Processing Units (GPUs) are the main contenders in this arena. Each has strengths and weaknesses in processing the complex computations LLMs require.

CPUs: The Traditional Workhorse

CPUs are the general-purpose processors in virtually all computing devices, from smartphones to supercomputers. They are designed to handle various computing tasks, including running operating systems, applications, and some aspects of AI models. CPUs are versatile and can efficiently manage tasks that require logical and sequential processing.

However, CPUs face limitations when running LLMs due to their architecture. LLMs require executing many parallel operations, a task for which CPUs must be optimally designed with their limited number of cores. While CPUs can run LLMs, the process is significantly slower than GPUs, making them less favorable for tasks requiring real-time processing or training large models.

GPUs: Accelerating AI

Originally designed to accelerate graphics rendering, GPUs have emerged as the powerhouse for AI and ML tasks. GPUs contain hundreds or thousands of smaller cores, allowing them to perform many operations in parallel. This architecture makes them exceptionally well-suited for the matrix and vector operations foundational to machine learning and, by extension, LLMs.

The parallel processing capabilities of GPUs provide a substantial speed advantage over CPUs in training and running LLMs. They can handle more data and execute more operations per second, reducing the time it takes to train models or generate responses. This efficiency has made GPUs the hardware of choice for most AI research and applications requiring intensive computational power.

CPU vs. GPU: Key Considerations

The choice between using a CPU or GPU for running LLMs locally depends on several factors:

  1. Complexity and Size of the Model: Smaller models or those used for simple tasks might not require the computational power of a GPU and can run efficiently on a CPU.
  2. Budget and Resources: GPUs are generally more expensive than CPUs and may require additional cooling solutions due to their higher power consumption.
  3. Development and Deployment Environment: Some environments may offer better support and optimization for one type of processor over the other, influencing the choice.
  4. Parallel Processing Needs: Tasks that can benefit from parallel processing will see significant performance improvements on a GPU.

Comparative Table

To provide a clear overview, here’s a comparative table that highlights the main differences between CPUs and GPUs in the context of running LLMs:


While CPUs can run LLMs, GPUs offer a significant advantage in speed and efficiency due to their parallel processing capabilities, making them the preferred choice for most AI and ML tasks. The decision to use a CPU or GPU will ultimately depend on the project’s specific requirements, including the model’s complexity, budget constraints, and the desired computation speed.

Hello, My name is Adnan Hassan. I am a consulting intern at Marktechpost and soon to be a management trainee at American Express. I am currently pursuing a dual degree at the Indian Institute of Technology, Kharagpur. I am passionate about technology and want to create new products that make a difference.

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