In personal computers, the front-side bus (FSB) is the bus that carries data between the CPU and the northbridge.

Intel Change to DMI or QPI due to physical limitation

DMI or Direct Media Interface is point-to-point interconnection between an Intel northbridge and an Intel southbridge on a computer motherboard

The Intel QuickPath Interconnect (QuickPath, QPI) is a point-to-point processor interconnect developed by Intel to compete with HyperTransport