Fully- and semi-modular PSUs allow for cables to be easily detached and stored. Fully-modular PSUs allow for every cable to be taken off, whereas semi-modular PSUs have cables that must be used, like the 24-pin cable, permanently attached. This allows for less clutter from unneeded cables, which can help airflow and aesthetics of a PC.
Modular power supplies also require additional depth due to the connectors and headers taking up more space, this is usually insubstantial, but could cause PSUs not to fit in cases where it is already a tight fit. Modular power supplies can also allow for easier customization of cables. For example, many people replace stock cables with cables that have each wire individually braided. Braided cables allow for color customization and many think braided cables look cleaner and classier than normal cables.
We moderate comments on a ~24~48 hour cycle. There will be some delay after submitting a comment.