<P> PCI Express protocol can be used as data interface to flash memory devices, such as memory cards and solid - state drives (SSDs). </P> <P> XQD card is a memory card format utilizing PCI Express, developed by the CompactFlash Association, with transfer rates of up to 500 MB / s . </P> <P> Many high - performance, enterprise - class SSDs are designed as PCI Express RAID controller cards with flash memory chips placed directly on the circuit board, utilizing proprietary interfaces and custom drivers to communicate with the operating system; this allows much higher transfer rates (over 1 GB / s) and IOPS (over one million I / O operations per second) when compared to Serial ATA or SAS drives . For example, in 2011 OCZ and Marvell co-developed a native PCI Express solid - state drive controller for a PCI Express 3.0 × 16 slot with maximum capacity of 12 TB and a performance of to 7.2 GB / s sequential transfers and up to 2.52 million IOPS in random transfers . </P> <P> SATA Express is an interface for connecting SSDs, by providing multiple PCI Express lanes as a pure PCI Express connection to the attached storage device . M. 2 is a specification for internally mounted computer expansion cards and associated connectors, which also uses multiple PCI Express lanes . </P>

How many sizes of pci express slots are currently manufactured for personal computers