[Nohmercy]

I know very little about the SGI cpu's so I hope someone can chime in here with some knowledge...

If I had a dual R10000 CPU lying around, and 2 single R12000 CPUs, could the 2 single R12000's be swapped into the dual R10000CPU to create a dual R12000 CPU?

[weblacky]

Every SGI that I've dealt with has a "Processor board" that contains mounted CPUs, not sockets, on a large daughter card of some kind. While I don't know if anyone has tried to swap CPUs onto CPU board that aren't configured for them, it IS known that Octane and higher CPU boards have EPROM programmed model info and often other parameters hard-set onboard to run the CPUs they came with. SGI DEFINITELY marketed in a way where you cannot "upgrade" to a dual CPU simply but "adding" a CPU into an empty socket. You had to purchase a Dual CPU card if you wanted a Dual CPU, or a Quad CPU card (for systems that had them) if you wanted it.

The card itself was supposed to have everything that made it modular (exception is PIMM for Fuel) but otherwise, SHOULD be swappable, that said, due to mainboard revisions of certain systems...newer CPU cards wouldn't work in older Mainboard revisions as well (generational issues).

This is precisely why DUAL/QUAD CPU card are SO MUCH more pricey than SINGLE, they are trapped as they are. People have done LIMITED CPU swapping, but only for CPUs that use the same pinout, voltage, and microcode and just needed their multiplier changed or something onboard the card. I think only O2 and maybe (memory fuzzy) Indigo2 had that happen so far.

If you're a hardware engineer, it's an untapped market...otherwise it's likely a dream (combining old high-end singles to make upgrades to lower-speed Dual CPU cards nito more variable higher-speed Dual cards).

[hamei]

Every SGI that I've dealt with has a "Processor board" that contains mounted CPUs, not sockets, on a large daughter card of some kind.

We used to swap out r10's for r12's all the time, and overclocked them as well. Lots of threads about this at nekochan. Dr Dave and Chicago Joe were both prominent in the discussions. Could be memory failure but as I remember all the processors up to 360 were socketed. 400's were the first soldered cpu's.

[weblacky]

Every SGI that I've dealt with has a "Processor board" that contains mounted CPUs, not sockets, on a large daughter card of some kind.

We used to swap out r10's for r12's all the time, and overclocked them as well. Lots of threads about this at nekochan. Dr Dave and Chicago Joe were both prominent in the discussions. Could be memory failure but as I remember all the processors up to 360 were socketed. 400's were the first soldered cpu's.

Correct, the cards are configured for the CPUs that are in them. To get other CPUs to work, you must change those configurations and if you hopefully don’t need an upgraded PROM (like the O2), the CPUs still needed to be pin and voltage compatible, yes? 

I didn’t say it wasn’t possible, only explained the restrictions of re-use a CPU card (unless you can design a new card for drop-in replacement for voltage and multiplier, hardware-only changes).  

I always figured the bigger problem was any initialization changes that had to be in PROM to support a new CPU, unless CPU was a natural drop/in upgrade for its predecessor.

[soviet]

In my case, got a bad motherboard in my octane 1 and removed the dual 250mhz r10000 cpu module.
Then installed it in another board that use to have a single R12000 on it. Worked fine right away.

[johnnym]

We used to swap out r10's for r12's all the time, and overclocked them as well. Lots of threads about this at nekochan. Dr Dave and Chicago Joe were both prominent in the discussions. Could be memory failure but as I remember all the processors up to 360 were socketed. 400's were the first soldered cpu's.

Can you detail this a little more, please? Did that swapping also require changing resistors for e.g. multiplicator or voltages? Are there any tables available about what's what on the processor modules?