Joost writes Other way around - Indigo2 had different mainboards for the different processors (IP22 for R4k, IP26 for R8k, IP28 for R10k), whereas O2 had a single mainboard (IP32) for all processors. The R10k/12k processors did have different mounting hardware, though (the R10k/12k module takes up one of the drive bays). The Indy's main limitation today is memory. It does not support SIMMS over 32MB, so it can have only 256MB RAM installed. A smaller limitation is the internal FAST-10/narrow SCSI interface (O2/Octane have Ultra/Wide). Still useable, though, and has the most gonzo startup tune I've heard anywhere (I have never heard of degrees of gonzo before this, though...) Definitely get 256MB RAM, 24-bit graphics, and IRIX 6.5.22 with the unused bits (especially ESP) chkconfig'd off (or 6.2 works well, too, but fewer software packages available). I wouldn't advise Indigo for a first system, they're a bit more tempermental and require the proprietary keyboard (try a few different PS/2 kbds in your Indy or above, though, as some don't work quite right). Octane came slightly after O200/O2000/Onyx2, the first release of IRIX 6.4 doesn't support Octane. The difference was only a couple of months, though. If anyone offers you an Octane, take it. O2s have the advantage of being small and quiet, but they don't seem to be as durable or as fast. It's getting to the point where Octanes with Vpro graphics are hitting the freebie bins (I'd like to find one...), and Octane supports faster CPUs, more memory, and faster graphics. The downside is (most likely) no PCI (the add-in PCI boxes are about $300 even now), but there are few drivers for O2 PCI (O2 doesn't support GbE cards, and I think there might be an issue with FC/SAS but I'm not sure there). That said I have a PI 4D/25, Indigo R3k/R4k Indy R5k, Indigo2 R4k, Indigo2 IMPACT R10k and an Octane 2x250/SSE (mostly running different versions of IRIX, the only double I have is 6.5 with the I2/R10k running 6.5.22 and the Octane running 6.5.30- the other beasts run 3.3.2, 4.0.5F, 5.3 and 6.2 (with one unused, I'm considering 5.1.1 there). They're all useable, but do bog down a bit with things like Firefox and OpenOffice. I do work on most of them, though (although the 4D/25 with 3.3.2 is mostly a "novelty" system - I haven't been able to find much of anything that runs under NeWS/4Sight).