You might be surprised - because they're pretty custom they are often "more open" than you might expect; as long as you have the connectors you can often get things running something. Sometimes they have bog-standard features present on the boards, just not enabled, etc.

It's the commoditized blade servers, etc that are stripped down to what they need to run and nothing more.

Oh I'm speaking from experience with the SGI supercomputer blades. They're pretty wacky, 4x independent, dual cpu boards per blade and all sorts of weird connectors and cooling and management interfaces. Custom, centralized liquid cooling that requires a separate dedicated cooling rack unit and heat exchanger, funky power delivery with 3 phase, odd networking topologies, highly integrated cluster management software to run them etc. I'm not sure if they have any sort of software locks on top of that, but I would bet they do and presumably NCAR wipes all of them so you likely won't have the software/licenses.

I dug up a link to some of the technical documentation https://irix7.com/techpubs/007-6399-001.pdf . Probably someone can get it working, but I imagine whoever is going to go through the hassle of buying this whole many-ton supercomputer is planning to just strip it down and sell the parts.

Yeah the licensing is often the stumbling block, unless you can just run some bog-standard linux on it. It sounds like this might be custom enough that it would be difficult (but I daresay we'll see a post in 5 years from someone getting part of it running after finding it on the side of the road).

Ultimately SGI was running Linux and AFAIK the actual hardware isn't using any secret sauce driver code, so yeah if you can get it powered on without it bursting in flames and get past the management locks you can probably get it working. It's definitely not impossible if you can somehow assemble the pieces.