[Raion]

An SGI Octane with either TRAM on an SI or a V6 is the bare minimum I would have for texture memory.

Others will recommend the O2, but there's a lot of "Gotchas" there:

1. PSU failures. They die randomly
2. RAM and upgrades are getting expensive. The supply dried up.
3. VERY fragile. It'll basically crumble in shipping. It's better to go for the Octane.

The octane does require 13w3 adapters, but it takes standard PS/2 peripherals.

I would not advise getting an octane without TRAM on an SI at least, because the TRAM allows for texturing operations to be at a reasonable speed.