[kaigan]

030-1872-006 Rev A.

Looks to be the same part. Mine's slightly older - 030-1872-005 Rev. A. Presumably the boards are interchangeable between the systems, then. That would allow someone to convert an Origin 350 over to an Onyx4 G2N if they had an AGP riser. They probably wouldn't have the ImageLink cables and backplate, but I doubt that's strictly necessary for operation.

Edit: On eBay, there is a seller who also has a Prism AGP riser with part number 030-2053-001. This is listed as a "Dual TIO AGP Riser". The TIO is an Altix-specific I/O ASIC used as a part of SGI's efforts toward reconfigurable computing. Maybe that version is designed to provide higher bandwidth for specialty applications?