SanDisk Optimus GX PRO 850X 1 TB M.2 PCI Express 4.0 NVMe TLC 3D NANDElite performance for champions. Champion your gaming sessions and creative workflows with the SANDISK Optimus GX PRO 850X NVMe SSD. Load levels fast and push through your creative workflow with PCIe 4. 0 Sequential Read Write speeds up to 7,300 6,600 MB s (2TB and 4TB models). With Random Read Write speeds up to 1. 2M 1. 2M IOPS (8TB model) and integrated SANDISK nCache 4. 0 technology, experience seamless game sessions and smooth multitasking.