The Dell Precision-3560 Mobile Workstation Supports Either 1 or 2 Drives Depending on Graphics Card Installed. (One M.2 NGFF (2280) or (2230) Solid State Drive with the Discrete Graphics Card Installed) or (Two M.2 NGFF (2280) or (2230) Solid State Drives with the UMA Graphics Card Installed) Note: Both of the M.2 slots support M.2 (2280) and (2230) Drives by moving the SSD holder screw to accommodate the form factor. (M.2 slot 1 supports Generation 3.0 x4 NVMe Drives and M.2 slot 2 supports Generation 4.0 x4 and 3.0 x4 NVMe Drives)