The Asus GL771JW Laptop Supports 1, 2 or 3 Drive Configurations. (Two 2.5" Solid State Drives or Hard Drives and/or One M.2 NGFF (2280) Solid State Drive) Note: If the 2.5" Drives were not installed from Asus, you will need the 2.5" Drive caddy p/n 13NB06K1AM0211 for installation. (The M.2 slot supports PCIe AHCI Solid State Drives)