Some luck was involved, but I also keep a close eye on certain auction sites.
I saw this nice looking O2 advertised with zero tech info ("used for a project a couple of years ago, has been sitting on a shelf since", i.e. I don't really know what it is and I want the space back), so rather than asking for hinv output or other numbers I asked the seller what the label on the bottom of the chassis said. The label had '400' in it. The next weekend I was in the neighborhood anyway for a Cirque du Soleil show and I picked it up.
Don't forget that for the average person any 400MHz CPU is ancient junk, and they're quite happy to take 100 bucks for something that has been eating dust on a shelf for the best part of a decade. Saves them a trip to the recyclers too.
I owned an O2 already (195 MHz R10K) which I sold for something like 50 or 75 bucks, so effectively the upgrade to the 400MHz R12000 was even cheaper
Now this is a deep dark secret, so everybody keep it quiet
It turns out that when reset, the WD33C93 defaults to a SCSI ID of 0, and it was simpler to leave it that way... -- Dave Olson, in comp.sys.sgi
Currently in commercial service:
In the museum
: almost every MIPS/IRIX system.Wanted
: GM1 board for Professional Series GT graphics (030-0076-003, 030-0076-004)