NGIO stands for Next Generation I/O is a specification from the extinct Next Generation I/O (NGIO) Forum that is designed to replace the Peripheral Component Interconnect (PCI) system bus. With today’s Pentium III processors and high-speed hard disks, the PCI bus is rapidly becoming the bottleneck that limits the performance of high-speed data center servers. The PCI bus is limited to about 500 Mbps of shared throughput. It lacks an error-detection mechanism and has relatively high latency. NGIO is intended to overcome these limitations. It uses a channel-based architecture that supports full-duplex transmission speeds of up to 2.5 Gbps.

The NGIO Forum combined its efforts with a group called Future I/O, which was promoting a different standard. The combined standard will be called System I/O; its development group is headed by Intel and IBM and includes Microsoft, Sun Microsystems, Hewlett-Packard, and Dell. System I/O is expected to reach the server market in the year 2001. It will use a channel-based I/O architecture instead of a bus architecture and will use from 1 to 12 wires, each having a throughput of 2.5 Gbps.

The channel-based architecture will allow different channels to carry different information to different components simultaneously, which will be a great improvement over parallel-transmission bus technologies. System I/O will also fully support hot-swapping of components.