Each frame, only a Region of Interest is rendered. Kinda like terrain fly-overs, but instead of terrain you might have a 3D seismic survey of the gulf of mexico, a high resolution CT scan, etc. The Octane architecture allows one CPU to be paging 3D textures in and out of memory, while the other CPU is doing the rendering. Finally, note the obvious point that Octane can have two CPUs while Indigo2 can only have one. See my R10000 performance comparison page for further details of processor differences between Indigo2 and Octane.
Octane leads the field at the moment for desktop workstations.
Thus, please remember that SE, SSE and MXE graphics options for Octane will be considerably faster than any equivalent Indigo2 configuration. The newer SE graphics option offers improved performance. Hence, SSE and MXE are considerably faster than any Indigo2 configuration. Lightscape XIO and memory bandwidth gives Octane a huge lead over all other machines. SE, SSE and MXE offer even greater improvements.