[jan-jaap]

I don't know of the GE Octane and Octane2 had specially modified mother boards to allow them to interface with GE MRI machines, but Mashek is selling a GE Indigo2 mother board for allot of money: https://www.ebay.com/itm/SGI-Indigo2-Mot...XQKAtRJxS9

You may want do do some research on this, as this may be a very nice find!

I found this complete GE Octane2 on ebay for almost 4k$... https://www.ebay.com/itm/SGI-Silicon-Gra...Swv9FXgweW

Onestly I think they're worth so much because of the configuration already setted and compatible with old GE MRs software. I also own original and sealed GE software for IRIX. I'm wondering how much that is worth

The GE Medical Systems ("GEMS") Indigo2 was definitely modified. It had more GIO64 slots for what looks like dual head High IMPACT graphics plus some custom boards. I imagine this required some modifications to the mainboard and/or PROM firmware.

That Octane labeled as a GE system looks standard as far as I can see, though it probably has a certain configuration that happens to work with the GE software or maybe it has a system serial number that happens to be licensed for the GE software.

There is also O2 mainboard revisions often labeled as "for GE MR equipment". This is the last ('1327') revision found in O2+, it has updated serial port chips required for the MR machine I believe.