The Dell Precision 15 7000 (7550) Mobile Workstation Supports up to 3 Drives. (Three M.2 NGFF (2280) or (2230) Solid State Drives) Note: The M.2 (2230) Drive can only be installed in slot 5. (All 3 M.2 slots support Generation 4.0 x4 and 3.0 x4 PCIe NVMe Solid State Drives)