The Alienware Area-51m R1 Laptop Supports up to 3 Drives. (One 2.5" Solid State Drive or Hard Drive and/or Two M.2 NGFF (2280) Solid State Drives) Note: If the 2.5" Drive was not installed from Dell, you will need the 2.5" Drive caddy p/n J8J5W and data cable p/n 2K51N for installation. (Both M.2 slots support SATA and PCIe NVMe Solid State Drives)