The Asus ROG GZ755GX Laptop Supports 1, 2 or 3 Drive Configurations. (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 Asus, you will need the 2.5" Drive caddy p/n 13NB0EU0AM0101 for installation. (The two M.2 slots support PCIe NVMe Solid State Drives)