A modular unit is a computer power supply where some (or all) of its power cables and connectors can be detached and removed.

In theory, using detachable power connectors (vs hard wired connectors for regular power supplies) will increase electrical resistance and therefore lower the efficiency of modular power supplies.

In a fully modular power supply, no cables come pre-connected giving you full control over your PSU’s cables. A semi-modular PSU offers modularity for the types of cables that aren’t used in every build.