Mix ups are impossible: different types of cables each have different pin-outs.
There is even a standard three-pin connector to report on fan speed inside this PSU.
Cables lock onto the power supply safely and securely.
Though the case includes a tray to keep cables organized and prevent any from going astray, it's a bit large for storing a few unused leads. This attractive plastic box is more likely to wind up at work or on fishing trips, where it can be better put to work.