Until the release of the AGP bus, video cards were installed in the PCI bus. The maximum theoretical transfer rate of the 32-bit PCI bus at 33 MHz was 133 MB/s, an insufficient rate for 3D applications (such as games, for instance) and that limited the development of more sophisticated video cards. Besides of its low transfer rate, the PCI bus had another problem: it was “choked”. The chipsets architecture used at that time was that of bridges, which used the PCI bus for the communication of the north bridge circuit with the south bridge one. Besides, most on-board peripherals of the PC were installed in the PCI bus, such as the on-board IDE ports, the SCSI controller, the on-board video, sound and network cards. No to mention the peripherals that could be installed in the PCI bus via PCI slots.