Hi

I have acquired a Powermac G4 AGP Graphics (Sawtooth) with a 350mhz processor.

I happen to have a 466mhz processor from a Powermac G4 Digital Audio that I upgraded some time ago - does anyone know whether would this be a straight fit into the Sawtooth?

It should fit in okay, I believe the cpu daughter boards are the same from Sawtooth to DA.

But if you do put the cpu in the sawtooth it'll only run at 350mhz unless you change the bus multiplier on the card. This is because digital audio G4s had a 133mhz bus vs a 100mhz bus on the Sawtooth.

Look it up on XLR8yourmac.com, they've helped me with jumper settings in the past.

Think about bus speed. Your 466 MHz CPU came from a machine which uses a 133 MHz bus speed and a PLL multiplier of 3.5 which means when you plug this CPU into your Sawtooth (100 MHz bus speed) you will have a 350MHz unit. Not so much a nice improvement. Without a third party CPU upgrade, you are going to have to use a soldering iron to overclock this puppy. Sorry.

The DA 466/533Mhz CPU are exactly the same design as older G4 CPUs - eg. 400/450/500Mhz models.

While you're adjusting the jumpers for this CPU to install in your Sawtooth, head first for the 5.5X multiplier - pretty much all of these CPUs overclock to 550Mhz. The DA533 is an even better CPU, hitting 600Mhz with no issues. Keep in mind to overclock this CPU, you can pop off the resistors then use conductive ink to short the relevant pins. I do prefer to resolder and reloate resistors while overclocking, but this way is quite alright.

The DA CPU is also a later revision of the G4, and runs substantially cooler than the original G4 cores

JB

Thanks people.

I dug out the old cpu and it seems to actually be a 533 mhz processor (part number 820-1175-A)

So, I could just drop the unit in and I would have a 400 mhz processor which was also cooler running, so perhaps worthwhile anyway.

If I want increased performance beyond this, I need to overclock by increasing the multiplier from 4 (can't find an exact reference) or upping the bus speed from 100 mhz (http://www.xlr8yourmac.com/systems/s...verclock.html).

What sort of stable increase could I hope for if I were to increase the multiplier? Would I need to increase the voltage or improve cooling?

Some months back, I found a few very handy pages that dealt with overclocking the older G4's, so I saved them to disk rather than bookmark them ... and it is just as well I did, because the site seems to be no more.

PM me, and I'll link you to a little archive I've built containing said pages.

B.

Beautiful. 600 MHz is on the cards

I believe that a 533 MHz CPU will run just fine at 550 or 600 MHz without anything special done to it like voltage boosting. Forget bus overclocking; it is never going to be worth it. As for cooling, considering the standard Sawtooth heatsink is fairly small, I'd suggest replacing the main case (120mm) fan with a new unit and that should probably do it.

The data sheet for the PPC 7400 is still available from Freescale (page 31 gives you your PLL multipliers: it's a .pdf)

not trying to hijack this thread but I have the dig audio dual 533 G4.
What could I do to and how far could I go to turn this into a beast?
Or would it be a case of save the money and get a newer come 2nd hand G5.

I've had a quick squize at xlr8yourmac.com and from what I can see I can install
a fairly fast proc upgrade.

cheers

You should start a new thread cactus

But monster upgrades would be

- Overclock dual 533 to 600
- CPU upgrade - eg. Gigadesign/Powerlogix/Sonnet 1.6Ghz + (even dual!)
- Radeon 9800 Pro


JB