Hm... it is indeed the 2-node InfiniteReality model. This page http://techpubs.sgi.com/library/tpl/cgi-bin/getdoc.cgi?coll=hdwr&db=bks&srch=&fname=/SGI_Admin/Onyx2_Desk_OG/sgi_html/ch03.html
says that if I have 1 node board I can run it on 110 volts. Do you mean by "usually desksides will do 120 just fine" that the system will boot and run on a US outlet with 2 node boards, but will trip the circuit breaker if it's doing something too intense? Can I disable the second node or remove it if the system is configured with two? (I doubt it but I might as well ask
Edit: The power supply does appear to be rated at 110V/16A or 220V/10A. I talked to someone at my university and he said that the orange outlets that someone else had claimed to be 220V were actually 110V but were isolated ground. It may not be a problem after all as long as I don't overload the circuits.
Nah, go ahead with the two-nodes. I'm just engineer-izing/attorney-izing - both of my systems work just fine on 110V, even with loads on all the CPUs. I just wasn't in on the design and can't say for sure and certain that it will work in 100% of all circumstances, especially with all disk trays loaded and XIO slots full, and I don't want your wife gunning for me when the breaker trips in the middle of a big "do".
If needed you can disable or remove the node, provided that you power down first. NUMAlink is very flexible about that. I don't think you'll need to. Perhaps borrow an amp-clamp from the university, power up the beast, and see what it really uses (I'm guessing probably around 1200-1300W, which would be slightly over 11A@120V once the power factor is taken into account). 240V outlets will be noticeably different from a 120V provided they were installed by someone with a clue (code pairs certain outlets with certain voltage/amperage combos).