http://techpubs.sgi.com/library/tpl/cgi-bin/getdoc.cgi?coll=hdwr&db=bks&srch=&fname=/SGI_EndUser/L1andL2Con_UG/sgi_html/ch02.html

See also: Robyn's notes on SGI power on/off

First, shut down the OS (if you don't know how to, or can't, do that, go away because you're wasting your time).

Next, if you haven't already, you'll need to connect to its console port. That ought to be documented elsewhere. Hint: it's currently on one of the CSCF console servers.

Then you'll want to power off all the bricks, it'll look something like this at first (bold is what you type):

N0000698-001-L2> pwr

001i01:
power appears on
001c05:
power appears on
001c08:
power appears on
001c11:
power appears on
001r14:
power appears on
001r16:
power appears on
001c18:
power appears on

So you want to do:

N0000698-001-L2> pwr down

WARNING: power on 001c05 console0 appears off

re-entering system console mode (001c05 console0),  to escape to L2

Now, all the bricks are off. But the system's main power is still on. I went and shut off all the switches on each individual brick (at the back) and the power bar, but that didn't get everything. LawrenceFolland says there's a master power switch somewhere. Perhaps he can chime in and say precisely where it is.