quick path interconnect (CPU) (QPI)

Quick Path Interconnect (QPI) is a connection concept from Intel with which serial high-speed data transfers between processors and other components can be carried out.

A QPI connection consists of two unidirectional channels for transmitting and receiving data. Intel works with symmetrical conductors over which the differential signals are transmitted. The QPI connections are implemented as point-to-point connections and are impedance terminated on both sides with on-die terminations( ODT). Alternatives for fast point-to-point connections on boards are HyperTransport( HT) and Ultrapath Interconnect (UPI).

The QPI bus consists of 20 data lines, 16 of which are used for data transfer. The architecture model supports the lower layers 1 to 5 known from the OSI reference model, including the transport layer. As a fifth layer, the QPI architecture model has a protocol layer that supports data packet switching between different devices.

The QPI concept achieves transfer rates of several gigatransfers per second (GT/s). The QPI bus is used in Intel's Core i7, among others.