A 3 slot PCI to XIO expansion module sometimes found in Octanes and Onyx2 or Origin 2000 machines.
Note that the location of the screws and the location of the XIO connector is different on the Octane compared with the Onyx2/Origin 2000. The Octane, the PCI cards are left to right and the O2K/Onyx2 its up and down.
See Octane subsection on case and expandabiity.
PCI slot IDs (in Hinv )
Octane without "Shoebox" PCI module
Adding/removing PCI cards.
The external screws in the O2k/Onyx2 one are above the PCI slots not off to the side like the Octane one in the above diagram.