Don't mix PSU cables between PSU models!
Modular power supply units — PSU
Nowadays, power supply units are modular or semi-modular: all or some-of the power cables are removable for cleaner cable management. Additionally, all cables become black!
Example of a semi modular PSU and some removable cables
Power connectors pin layout
Power connectors are standardized on the device side (ATX mother board, PCIe Graphic Connector (PEG), SATA memory drives, "Molex", etc.).
Unfortunately, power connectors are NOT standardized on the power supply unit side!
See also: Refer to PSU Cable Compatibility and Pinouts external web site for a quite comprehensive list of pin layouts from main PSU manufacturers.