SGI's flagship graphic workstation until November 2000 when the Octane2 was released (Really just a graphics upgrade), before that the Indigo2 was SGI's main workstation. Octanes are extremely capable machines (Although the inital Octanes had some issues that caused them to crash.) and their technology is based on that of SGI's Origin supercomputers. Despite only being made as remanufactured systems, they have been used in almost every movie lately that has employed computer graphics in some way, including Final Fantasy: The Spirits Within.
Originally, the Octanes used the same cards as the IMPACT graphics in Indigo2s, only renamed as SI (Solid IMPACT), SI with texture (High IMPACT), SSI, MXI (Maximum IMPACT). Later, the IMPACT graphics were improved and became SE, SE with texture, SSE, and MXE. Along with the graphics upgrade, the Octanes were upgraded from 175MHz and 195Mhz R10000s to 225MHz R10Ks and eventually R12Ks.
As mentioned above, the Octane uses technology from SGI's high-end supercomputers. The main feature of this is the Crossbar memory system. There is no bus on the Octane. What exists instead is a 8-port-no-blocking-high-speed crossbar switch. This is the exact same thing found in the Origins with minor modifications and allows the Octane to have a maximum of 1.6GB/s transfer rate. It also uses 3 proprietory XIO slots and additionally, can have 3 PCI64 slots added.