Alienware 17 R4 Setup and Specifications
Storage Table 7. Storage specifications
SATA 6 Gbps•
PCIe up to 32 Gbps
One 2.5-inch drive
Solid-state drive (SSD)•
Two full-size M.2 PCIe/SATA drives•
One half-size M.2 PCIe/SATA drive
search for "New Alienware 17 R4: Upgrade/Replace M.2 Solid State Drive" video on YouTube...
Look at video at 1:14.....shows it above larger m.2....