Powerbook G4 12" - 867mhz - MPC7440 - schematic or overclock info?

[Akulareb]

Hello lovely forum,
I've acquired a 867mhz with the intention to overclock it.
Its battered, but was nice to discover it has 1gb of ram and a working battery.

Looking at Everymac, this model was supposed to have a 7455, but looking at motherboard pictures shows 7440 (low power version of the 7455) which is the same processor used on the gigabit Ti (667mhz).

Does anyone has the schematic of the logic board? 820-1385-a is the model number.
I can't find anything online.

I am very confident when it comes to soldering, and already overclocked few powerbooks and iBooks like Ti to 1.2ghz & a 17" to 1.83ghz.

In addition I can only theorise that a frequency of 1ghz would be unobtainable, given the Ti topping at 667mhz, and given that it's a low power version of the MPC7455.

But maybe like the Ti, a slight over voltage would do the trick.

Happy to document my findings.

also it's funny to discover that the first Ibook g4 800mhz has a 7457 & USB 2.0

thanks in advance

 

[ervus]

I think the 12" PowerBook models were all pretty similar, so the same resistors should work to configure the 867MHz model. But for this one I would personally be more interested in underclocking it. If you reduce the voltage and clock speed you can probably get it to run significantly cooler.

For a fast 12" PowerBook, I would start with the 1.5GHz model. This one has a much faster CPU that can also run at half speed (DFS) to save power/heat. I think at half speed it would still be faster than the 867MHz model and use probably half the power. It also has faster RAM, more VRAM, etc.

 

[Akulareb]

I think the 12" PowerBook models were all pretty similar, so the same resistors should work to configure the 867MHz model. But for this one I would personally be more interested in underclocking it. If you reduce the voltage and clock speed you can probably get it to run significantly cooler.

For a fast 12" PowerBook, I would start with the 1.5GHz model. This one has a much faster CPU that can also run at half speed (DFS) to save power/heat. I think at half speed it would still be faster than the 867MHz model and use probably half the power. It also has faster RAM, more VRAM, etc.

Oh, I have no experience with a 867, good to know they run on the hot side!

1.5ghz was my first choice considering also the two finger scrolling and to bring it at least to 1.67ghz, but they're quite rare. A 7448 swap I'd imagine would also be possible with the right modified rom.

Heard of people swapping the 1ghz motherboard with a 1.5 albeit minor modifications, altho the 867mhz looks like a different beast, and potentially PLL wise might be different resistor markings.

Ta

 

[ervus]

If you post some good pictures of the PCB we might be able to help you figure out the settings.