[exalsG4]

Now, as I already said I'm not an SGI expert, so I'm having troubles identifying some components. I know there is the PCI upgrades modules with fiber card and an external SCSI card, and I know that the Graphics board it's a VPro, but didn't understand which VPro this is. Also I can't identify the CPU or the quantity of RAM installed.

Based on the model number CMNB015ANG270, it's a single 270MHz R12000, right about at the middle of the possible processor options. I can't identify the ram modules, but there should be a part number on them. Alternately, you should be able to get an hinv from the prom once you turn it on.

Based on the part number 030-1241-002, it looks to me like you have SE graphics rather than VPro

Correct, SE gfx with Texture Option RAM.

You also have a later 1467 motherbodoard, which is good from an upgrades and RAM point of view. You can take dual 600Mhz CPU PIMM and 8Gig RAM.

Another + is you have a Cherokee PSU, which means you can run VPro gfx cards.

Check in your hinv if you have a 1.3 or 1.4 XBow, this will determine if you can run V6/V8 (1.2/1.3 xbow) or V10/V12 (1.4 xbow). I highly suspect you'll be running a 1.3 xbow.

Those look like non-sgi branded dimms, so they may have a sticker somewhere to indicate the ram kit size. Ram is installed in pairs or 'kits' so it could be anything from 64mb kits to 2Gb kits (unlikely though...)

Sticker residue / glue can be removed with a bit of white spirit (turpentine) on a cloth, do not use a scourer. Clean off with general household cleaner and water after.

Bit of spit and polish and you should be good to go! With a gig of Ram that Octane will be fine for general late 90's software use. Don't expect it to run Firefox well as just about any mips SGI system struggles with gtk2+. If you use it with a late 90's software mindset you'll enjoy it.

Thank you for being such clear in the details! In the same warehouse were I rescued this machine there's a blue Octane2.
These computer are 25kg monsters, so my plan is to also rescue the other Octane, check the specs, swap the better components in one of the two (I can't decide which!) and sell the other to a good home.
I would love to keep both, but I literally don't have the space :(