SGI: Hardware

So I recently came into an SGI O2, and got around to sticking it into a less-beat up chassis and firing it up.
hinv reveals that there's 128Mb of RAM - more might be nice but that requires finding some and all I'm going to use this box for is a constant IRC fix, and more to the point here, an R10K 150Mhz chip.
Some confusion and googling later (I've been up for far, far longer than I normally am) leaves me with some interesting knowlege of mods that have been done to the O2 - but so far only for the R5K as I saw.
Oh yes, interesting it was to learn that I could cram a 600Mhz chip in there (Should I find one), or overclock the 180Mhz R5K to 200 - if I had one.
But I don't. I've got the apparently less-common R10K - albeit at the slower of the clock speeds.
Now, having failed to find anybody else apparently crazy enough to try what I'm proposing, and recalling this unlikely-named website from watching a friend pop in here to show stuff off to me in the past, I figure I may as well hop in here and see if anybody can help
Right, rambling and tangients aside, the point I've been (And apparently still am) loitering around, is that I've got 4 R10K 200Mhz chips that have been sitting in a tray with some PIII 1.4s - pulled them from some other SGI monstrocity I was watching get plain and simply scrapped figuring (Well they look damn impressive, if nothing else anymore), and now realized that I could well potentially use one to upgrade this O2.
Now were this a PC, I'd simply know that I could just drop one chip that's a little faster in place of the old one - sockets generally stay pin-compatable with eachother.
But being that this is an SGI, and I'm not exactly familiar with what goes on on that CPU module board that's specific to a chip, I'm being a little more cautious about this, and decided to find out - Can I do this? Is there any difference between the module boards for the 200Mhz R10K and the 150? Will I blow anything up? Do I perhaps need to break out a soldering iron and move some resistors about, or hunt down a new clock crystal?
Should this work, can I perhaps even overclock the 200?
I'm at a loss here, unsure of where to go next. Obvious choices are to do an install, but I'm rather lacking in anything to install onto here. There was some annoyance with the eject gearing on the CDrom being broken, but that's since been remedied, and I'll probably have something to install this by tonight.
Anyhow, enough of my ramblings. Time to click 'Submit'

The 150MHz and 195MHz CPU Modules are different in that the 195MHz's glue chip isn't as buggy, i.e. the 150 and 175MHz modules drop frames when recording video. I think the CPUs itself should be swappable, to adjust the internal clock multiplier, You'll have to swap some SMD resistors. I'd think that the 150MHz runs at 75MHz * 2, so 187 and 225MHz should be the next possible steps without swapping the clock chip. I think the entire 150-200MHz R10k range runs at 3.3V, and at least from 250MHz on, the core voltage is separate from the 3.3V i/o and lower than that. There's a longish thread around here on upgrading the 250MHz O2 modules to 350MHz R12k.

It would be easier to just buy a 195MHz Module, I think I still have a spare one somewhere.

R1xk is mostly compatible, the only issues are:

* over 200MHz uses 2.5V, whereas 195 and lower (first-gen) use 3.3

* Over 300MHz moves to BGA packages rather than socketed LGA, so replacement becomes much more difficult

* R10K/R12K/R14K/R16K have slight architectural differences that need to be explicitly supported by IRIX and the PROM (more so for R10K/R12K, tapering off for the other ones, but also the number of machines that used them and availability have tapered off as well, so no one has tried a R16k in an O2 to my knowledge). This is why you're extremely unlikely to see a R12K/300 Indigo2 or Onyx1.

As was pointed out, O2 has its own issues relating to the early R10k hack attempts by SGI.

Easy is relative to each person. For a person with the money to spend on shipping and a way to pay online, sure, just buying a new part is easier. For a person trying to make use of what's already been acquired, and not wishing to spend anymore money on more old and obsolete hardware(As high end as it may have been), simply buying more to add to clutter and unused parts is less desirable, and not as easy if they don't have the money in the first place.
That being said, it's good to hear I should have little trouble hacking the chips I've got in place of the slower one in there, though if I could get a link to the thread in question that was mentioned that would be nice. I did a little spelunking through search results and found some stuff, but nothing that seemed directly related to unorthodox upgrades of the R10K module, though a couple interesting threads had dead links to images that could have proven interesting.
If there's anything else I should know about this machine, by all means, lead me in the correct directions.

Azazel wrote: If there's anything else I should know about this machine

Not machine related, but R10K CPUs labeled "200MHz" won't run at 200MHz due to some timing bug in the design. Depending on the system they run at 194MHz (Onyx1) or 195MHz (everything else).

So if you hack a 200MHz chip into a 150MHz module, jumper it for 195MHz, not 200.

Is there any special way to do this, or should I just spend a good ten minutes pouring my eyes over the module board?
==Edit==
Found the jumpers in question, just a matter of finding out in what way I need to move them to affect the multiplier.
==Additional edit==
It occurs to me I'll need to find something to put in place of the odd soapy thermal padding that's on the 150mhz chip, as if I simply drop the 200 in place of it I'm going to need something to press it against the board to maintain contact with the LGA pins.
Still trying to remember where I saw photos of a couple o2 CPU modules for that matter.

I'm curious how you've gotten on here-- or is no news an indication of no change?

Would this be the kind of thing I should go and annoy him about?