In general, if you're faced with this choice, I would say go with Onyx2, ie. if you're considering the very top end of an Octane's current capabilities, then there is a danger that you will have no room to grow your computational resources should project requirements exceed original expectations - a common occurence I expect. Think of this as rather like buying a hifi speaker system: if one finds oneself contemplating the very top-end of a particular model's capabilities, then one should get the next model up that can handle the task easily, rather than at the peak of its capabilities.
This page gives some detailed examples of why Onyx2 is the better choice when faced with such a decision in the world of 3D real-time graphics, especially VR. Obviously, there may be budget limitations which leave one with no choice, but my comments here are targeted more at customers who tend to have higher budgets: aerospace, automotive, government, medical, oil industry, etc. Such industries would prefer to go with cheaper systems whenever possible, but they're much more likely to select a faster system if they believe there is sufficient justification for their purchase or lease. When it comes to what I call 'industrial' quality projects, it is unlikely that managers would be so short-sighted as to limit the scope of a research program by under-equipping the research team. The team's focus should be on the problem, not on getting round the limitations of their equipment.
Many of the comments I give below are based on an email I received from someone working on an automotive VR research project who had exactly the above conumdrum to solve. First some summary tables to convey the basic differences between Octane-MXE and low-end Onyx2 as they are right now (this data is extracted from my SGI Graphics Performance Comparison Tables page; see that page for a 'key', eg. 'R' = Reality, as in Onyx2 Reality):
3D Flat Lit GZ Lit Lit X Depth Tri Tri/sec Tex GZ Lines Cued GZ Strips GZ Indep Lines No Z Tri/sec Quads Octane MXE: 3.88M 2.29M ? 2.19M 1.42M 880K Onyx2 R: ? ? ? ? 5.5M ? Onyx2 IR (9): ? ? ? ? 11.0M ? Onyx2 IR2 (9): ? ? ? ? 13.1M ? GF Tex GFZ Conv(3x3) Conv(5x5) Color Pix/sec pix/sec Lookups/sec Octane MXE: 240M 138M 33.7M 27.12M 96.4M Onyx2 Reality: 448M 188M ? 30M ? Onyx2 IR (9): 896M 624M ? 60M ? Onyx2 IR2 (9): 896M 768M ? 60M ? Data CDRS Design Advanced Lightscape Explorer Review Visualiser OCT MXE/250: 18.37 55.46 10.62 20.09 1.55 Onyx2 R/180: 21.72 91.54 15.83 23.70 2.41 Onyx2 R/195: 21.90 92.72 16.27 23.84 2.61 Onyx2 IR/195: 35.65 161.29 20.82 45.43 2.65 Onyx2 IR/250: 41.60 ? 23.96 ? 3.30 Characters Screen Max Framebuffer 3D Vectors Per Second Clear Memory Size Per Second Octane MXE: ? ? 27MB ? Onyx2 R: ? ? 80MB ? Onyx2 IR: ? ? 320MB ?
Please don't ask me when new products will be released as I honestly have no idea. One can merely judge from common sense that Octane's current graphics technology, which is based the IMPACT technology from the old Indigo2 days, is showing its age, while InfiniteReality in its basic form is more than 2 years old now. With the release of the Visual Workstation, I find it highly unlikely that the current options for Octane and Onyx2 would be left alone for much more than a month or two.
So, why is Onyx2 better than Octane for VR projects, etc.? Here are some reasons:
Having a fast graphics system is no use if there is insufficient main CPU power to handle application overhead. Plus, complex projects may, for example, require setups such as 3 or more simultaneous video outputs; for efficient processing and reliable performance, it is common to organise such projects by allocating different CPUs for distinct tasks. Exactly what is appropriate depends on the specifics of the application.
It is not possible to get the most out of a graphics system like InfiniteReality without having good main CPU power, and that means - for tough problems - at least 4 CPUs. My SGI General Performance Comparisons page has some examples where the speed of an Onyx2 InfiniteReality is limited by the speed of the main CPU rather than the graphics system.
For VR work, high frame rates are critical; those involved with video conferencing technologies have found a negative effect if the frame rate of a video link is too low - in the same way, a VR display will not be able to offer good insight into solving a problem if the display update rate is low (the level of interaction and cognitive would be insufficient to gain any further understanding of the problem).
In the above example, where at least 3 displays are required (more likely 4 since an instructor display is also usually needed), again Onyx2 is the choice since an option card offers up to 8 display outputs whereas I believe Octane is limited to 2.
I know of a researcher at a medical institution in Alaska who was organising an upgrade to their SGI system. They were considering an Onyx2 Reality as an upgrade over their old IRIS Crimson. After some consideration and demonstrations, they eventually chose InfiniteReality instead (2X faster than Reality). A wise move.
Your focus should be on solving the problem, whatever that may be: research program, specific task, etc. Don't obtain a system that can't help you solve your problem.