[johnnym]

Purchased a branded SGI gigabit card from ebay it was 50$ and brand new so it seems was a good option.
The card is marked like "SGI 9470434 Gigabit Ethernet" inserted it onto the pci slot on my O2.

Does it actually work in one of your other machines? There's still the option that it's just broken. I have removed a bunch of these from my Origin200s (both copper and fibre ones), so I assume this card is absolutely supported in IRIX. In addition I know for sure that one of my Origin200s was originally used as file server with some of these cards installed, so this must be a supported configuration option.