The system bus The system bus connects the CPU with RAM and maybe a buffer memory (L2-cache). The system bus is the central bus. Other buses branch off from it. The system bus is on the motherboard. It is designed to match a specific type of CPU. Processor technology determines dimensioning of the system bus. At the same time, it has taken much technological development to speed up "traffic" on the motherboard. The faster the system bus gets, the faster the remainder of the electronic components must be.