An optional PCI card cage with one half-height and two full-height PCI slots can be added to any OCTANE system. The PCI card cage allows expansion of up to three industry standard PCI-32 or PCI-64 cards for special networking, storage or other I/O requirements. The PCI card cage is a plug-in module that fits into the back of the chassis between the disk drives and the power supply. PCI add-in cards are inserted into a PCI backplane within the card cage, which then plugs into the chassis and connects to the system frontplane.