The Dell Alienware 17 R5 Laptop Supports up to 4 Drives. (One 2.5" Solid State Drive or Hard Drive and/or Two M.2 NGFF (2280) Solid State Drives and One M.2 NGFF (2242) Solid State Drive) Note: If the 2.5" Drive was not installed from Dell, you will need the 2.5" Drive caddy p/n GWD21 and data cable p/n KG0TX for installation. If Installing a M.2 (2280) Drive in empty slot 2 SSD-2 or slot 3 SSD-3, you will need the M.2 Drive thermal heatsink bracket p/n JV98R for installation. (M.2 slot 1 SSD-1 supports M.2 (2242) SATA and PCIe NVMe Solid State Drives - M.2 slot 2 SSD-2 supports M.2 (2280) PCIe NVMe Solid State Drives only - M.2 slot 3 SSD-3 supports M.2 (2280) SATA and PCIe NVMe Solid State Drives)