Overclock G4 Gigabit 500MHz DP Processor Card – Help with jumpers

[macinbot]

I need help figuring out which jumpers / resistors to adjust for overclocking the G4 Gigabit DP processor card.

I am slowly chugging along with my G4 Gigabit Budget Upgrade project. I want to overclock its G4 500MHz DP card to 600MHz. From this post on XLR8YourMac, there are two, or maybe three, areas with jumpers that set the clock multiplier.

https://www.xlr8yourmac.com/G4ZONE/sawtooth/Dual_G4_550_mods.html

To me, it's unclear in the post if the third callout at the bottom of the card (near the connector pins) is supposed to be changed as well.



So I'm unsure if it's just the two sections: The jumpers in multiplier section on the front of the card, and then the jumpers near the processors on the back of the card?

Or is it all three sections that need to be adjusted? And if so, what would be the configuration in that third section on the bottom near the connector pins? The jumper layout is different, with only three pads (instead of four) to adjust the jumpers (see my photos below).

From the post, it looks like the jumpers for the multiplier section in the front, and two sections on the back are flipped (though I suppose it depends on your orientation). And from the post, here is the multiplier chart:



So, what I'm getting from the post is that all the jumper sections need to obviously have their jumper configuration changed. And the config goes for the 500MHZ DP goes from this:

• OPEN
• JUMPER
• OPEN
• OPEN

And changes to this for 600MHZ overclock:

• OPEN
• OPEN
• JUMPER
• OPEN

As a guy who hasn't soldered in a very long time, and who absolutely does not excel at SMD level soldering, I want to make sure that removing the resistors and running straight solder trace across is fine. I believe that the resistors are null value and just act as jumpers.

And being that guy who hasn't soldered in awhile, recommendations for iron temp when performing this kind of work? (FYI: I have flux and a desoldering braid)



Three sections of the processor card in question...

Front bottom of processor card:



Back Processor Card near processors:




Back Bottom Right near connector pins:

 

[macinbot]

Bumping in hopes anyone has insight on this before I throw caution to the wind...

 

[herd]

The web page you linked is correct. I think 550MHz is more likely to work--I would suggest trying that first. Just add two resistors. Then you can try 600 on each CPU one at a time by removing the original resistor for each CPU. The resistors are 1k ohm (labeled 102) but I think people have used all kinds of things including pencils and various types of conductive ink, etc.

Good luck, and let us know how it goes...

 

[macinbot]

Thanks for the reply. My biggest question is the last pic in my post – with the three instead of four jumper pads (resistor marked "471"). It's called out in the XLR8YourMac post graphic, but nothing is mentioned about what, if anything, to do with it.

But otherwise, yes, I was going to clear all the pads and then use a circuit pen to connect the jumpers. Aiming for a 600mhz DP overclock. Think I'll work backward from 600MHz down to 550MHz, as if it's unstable at 600MHz, it's just a matter of adding an additional jumper, as opposed to adding two and then removing one.

I do like the idea of one CPU at a time, and I'll try that route.

Going to use MacBench and GeekBench to get benchmarks. Looking for suggestions for long term (potentially hours) stress testing if anyone has any.

 

[cobalt60]

May I suggest you try OC'ing your bus to 120MHz? Link on the procedure is in my sig.

If your CPUs are 7400s (which they appear to be), and not 7410s, then I don't think you'd get 600MHz, and 550MHz would be cutting it close. 7410s were good overclockers, 7400s were not. That said, I couldn't get a dual 533 7410 stable at 600 without a voltage boost.

So I think a 120MHz bus and running the CPUs at 540MHz would be your best bet.

 

[macinbot]

Thanks for the idea