So can you take a Rev A iMac that high?

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doug-doug the mighty's picture
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So can you take a Rev A iMac that high?

This thread is a slightly off topic extension of coius' thread G3 400MHz Achievement.

I do not know a great deal about the G3 AIO other than it was a 233MHz, just like my Revision A iMac. Somewhere, I think I still have notes on the jumpers involved in clock chiping the iMac, but I never went through with it.

Does anyone know if you could take an iMac as high as coius took his AIO?

And if you cannot, what makes his AIO so different from the iMac that the AIO can handle it?

Eudimorphodon's picture
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Well...

It says in the Coius' thread that he was overclocking a 300Mhz ZIF, not a 233Mhz one. It's noted offhandedly that prior to getting the 300Mhz one he was overclocking the original to 280Mhz.

People have achieved 400Mhz in original iMacs, but doing so generally requires starting with a CPU board from a 333Mhz model. (The CPU boards are compatible between all the tray loaders, and came in 233Mhz, 266Mhz, and 333Mhz flavors.)

So... the answer is "Yes, you can probably get to 400Mhz, but not with a 233Mhz CPU". Does that answer the question?

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Furthermore, overclocking the

Furthermore, overclocking the iMacs involves moving small SMT resistors, not moving normal jumpers. You may be able to overclock successfully, but as Eudi notes, you probably won't see a significant jump. My experience with G3s is that you can generally get about 50MHz more out of them before they become unstable, but some people have been able to achieve bigger jumps.

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My (no longer owned) 233MHz r

My (no longer owned) 233MHz rev. A iMac was able to clock up to 266MHz.
300 MHz gave me a grey screen, but I've read of others able to hold a stable 300. YMMV, and yes, the resistors are dang tiny.

doug-doug the mighty's picture
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ok

yeah, I knew about the 'jumpers' being resistors, but I also knew that they were actually 0 Ohm, meaning that they work like jumpers despite being soldered on SMT components.

I did indeed miss the reference to the 400+MHz starting off as a 300.

oh well, it was just a glimmer of hope that I could break 300 and be stable.

Thanks!

madmax_2069's picture
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didnt that version of iMac ha

didnt that version of iMac have a cpu that could be upgraded or was it a diffrent iMac that has the removable cpu

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rev A 233 -> 300 = yes, rev D 333 -> 400 = yes

Done both with a rev A (or B, I forget just now), both worked fine. Many G3s of all sorts from this era can be seriously overclocked, the parts were frequently well underspecced.

I expect some 233s might even go to 333, but I never tried it with any of my available CPUs.

Also, in case anyone is curious, I did find a rev D MLB which I put into the revA/B iMac, along with the 400MHz CPU, in the hopes it'd prove to be capable of playing DVDs. It could (using VLC) but the herky-jerky results were unsatisfactory. Otherwise, it's proved (under Panther) to be a very usable, snappy machine.

dan k

doug-doug the mighty's picture
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yes

I know that the A and B did, I think all of the candy colored and snow/ice iMacs had removeable processors.

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re: yes

Right, that's the revs A (233MHz) through D (333MHz) trayload G3 iMacs only. No other iMacs have removable CPUs. Well, not without some serious desoldering tools that is.

The AIO has just regular Platinum (ick, I hate the word Beige!) G3 MLB with a ZIF CPU socket. Lots of ZIF G3/G4 CPUs out there that'll fit, from 233 on up to at least 1GHz. So faster CPUs are easy and cheap to come by. That's not the case with the revA-D iMacs, very few faster CPUs are available for that special CPU socket.

dan k

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