Switch CPU module on a G4 MDD.

Question

Level 1

13 points

Switch CPU module on a G4 MDD.

Hello everybody.

Today I bought myself an old Power Mac G4 MDD with a Dual Processor CPU, running at 867 MHz. Looking around the Web for possible upgrades, I noticed that the other Dual Processors modules for the MDD models (1 GHz and 1.25 Ghz) have almost exactly the same shape as the one I have. Even though, I'm not sure if it is just buy it and switch it, because, seaching for more information on the subject, I found out that the 867 Mhz processor have a front side bus at 133 MHz, and the 1 and 1.25 GHz are at 167 MHz, and honestly I have no idea ow that will affect the computer. Any help will be sincerely appreciated.

PowerMac

Posted on Jun 15, 2014 8:57 PM

Reply

Answer 1

Jun 15, 2014 11:02 PM in response to jz793

A processor that runs at 1.25GHz on a 167MHz bus would run at 1.0GHz on a 133MHz bus.

The processor's multiplier can be changed to get the speed back. Some soldering is required.

http://www.xlr8yourmac.com/systems/g4_mirrored_drive_doors/G4_MDD_CPU_Module.htm l

Reply

Answer 2

jz793 Author

Level 1

13 points

Jun 16, 2014 8:34 AM in response to Dave Hamilton

Thank you for answering, Mr. Hamilton.

If I am getting this right, the French man added a resistor and the CPU began to work at 167 MHz, and that was the only modification he made. So, the difference on the front side bus will not affect me (except for changing the DDR type for them to work at 167 MHz) if I get another CPU module. Am I wrong?

Reply

Answer 3

BDAqua

Level 10

250,619 points

Jun 16, 2014 1:22 PM in response to jz793

Hi, you won't be cahanging the Bus speed or RAM speed, you'll be changing the multiplier for the CPU, or Bus Ratio to make the CPUs run at whatever you get, 1.0 GHz or 1.25 GHz, 7.5 or 9.5

Reply

Answer 4

jz793 Author

Level 1

13 points

Jun 16, 2014 6:05 PM in response to BDAqua

So, given the fact that the CPU multiplier is also on the same card (the processor daughterboard), I can get the daughterboard with the other processor (namely the 7455 @1.25GHz) and connect it to the same motherboard without any other changes, despite the fact that the FSB is higher than the one it has right now. That will be my question.

Reply