# PCI Express PCI Express (PCIe) is a high-speed serial interconnect used for internal devices and storage. The Mac Pro packaging describes 256 GB of PCIe-based flash storage. ## Source [[Scanned_20260730-1230#PDF Page 29|Scanned_20260730-1230, PDF page 29]] The label identifies the original storage class and capacity, not later replacement, encryption, health, contents, or retention state.