A modular power supply is a type of power supply unit (PSU) used in computers that allows users to connect only the cables they need. This design helps reduce cable clutter inside the computer case, improving airflow and making it easier to manage components. These power supplies typically come with detachable cables for various components, such as the motherboard, graphics card, and storage drives. By using a modular power supply, users can customize their setup, making it more efficient and organized while ensuring that the system receives the necessary power for optimal performance.