The PowerMac G5 is a desktop computer first produced in 2003 by the Apple Corporation. This guide will review the repair process of an Apple PowerMac G5 model number A1047 EMC 2061 from 2004. It was discontinued in 2006 as part of the Intel switch first to developers then consumers.

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One core of four (CPU A Core 2 Diode) Runs Really Hot

I have a Power Mac G5.

Hardware Overview:

Model Name: Power Mac G5 Quad

Model Identifier: PowerMac11,2

Processor Name: PowerPC G5 (1.1)

Processor Speed: 2.5 GHz

Number Of CPUs: 4

L2 Cache (per CPU): 1 MB

Memory: 12 GB

Bus Speed: 1.25 GHz

Boot ROM Version: 5.2.7f1

Lately the fans run loud so I installed Hardware Monitor and it appears that CPU A Core 2 is running into 90°C while all the other cores are staying below 60°C.

Can this be right? Wouldn't CPU A Core 2 be under the same die as CPU A Core 1?

Can anyone say why this might be happening and how I can fix it? I build computers and I'm not afraid of pulling the LCU out and re-applying thermal interface, but it sounds like the design of the computer might make that difficult.

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Chosen Solution

You may have developed a coolant leak. You'll need to do some reading on this, but here's a start:

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I have inspected the inside of the case and see no signs of a coolant leak. However, I just noticed that the one core that is overheating, also has a higher voltage and current than the other three by 16-20%, the overheating core has a voltage of 1.29 - 1.35 while the others are 1.18 - 1.21, also, the Current is 23A while the others are 20A. I'm supposing this isn't a coolant problem, however, it doesn't look good for my old workhorse!

I suppose, before I do anything more I should reinstall Mac OS, just to be sure.


Make sure you have the original system installation disk with the fan sycning software because any major changes will require it or your fans will run wild.


I don't have the original disks, which were 10.4, I'd be installing directly with 10.5. Where can I find the fan syncing software? I have the full OS X 10.5 Install disks for all Apple hardware.


Call Apple and request the original installation disk with the AHT and fan syncing utility, it will not be on a retail 10.5 disk. They should charge you $16 for it plus shipping and tax.


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