Both a SATA and a power cable are necessary. There are usually enough power cables on the power supply unit.

Samsung Electronics GmbH
Hello,
Thank you for your enquiry.
The Samsung SSD EVO 870 is a data carrier that connects directly to a motherboard. This requires a SATA interface and a free mounting slot in the 2.5 inch form factor. There are no cables in the original delivery accessories.
Kind regards from Schwalbach
Your Samsung Service Team