The Dell Alienware 15 R2 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/carrier p/n 8FGT2 and data cable/connector p/n DCR9X for installation. (Both M.2 slots support SATA only Solid State Drives)