Logic Board removal on a Power Mac G5

Hello All,

I have searched the internet for this information but can not find it any where. Are there any guides on removing a logic board from an older not intel base mac g5? I would also like to gut the whole case if possible and maybe use it or sell it. I have gotten the cover off and removed fans but there seem to be some hidden fasteners holding the heat sinks on the ppc processors.

Jack10525 said:

Hello All,

I have searched the internet for this information but can not find it any where. Are there any guides on removing a logic board from an older not intel base mac g5? I would also like to gut the whole case if possible and maybe use it or sell it. I have gotten the cover off and removed fans but there seem to be some hidden fasteners holding the heat sinks on the ppc processors.

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I would agree...this info does not seem to be easily or commonly available. But here's something I found that may at least be a little bit helpful:

How to Replace a G5 Logic Board | eHow.com

It's not exactly a "DIY" step by step procedure...but it does mention that:

But the good news is the G5 was engineered to fit together logically, so there are no "tight squeezes" as far as replacing components.

I would take this to mean that it comes apart & goes back together in a "logical" fashion...and if someone is experienced at taking things apart & putting them back together, would not find the disassembly too difficult.

Good luck,

- Nick

Hey thanks for the reply. I didn't find that one and have been searching the net for the last week. It's not a bad guide but is not specific enough. There are some screws or fasteners I can not find on the g5 I am taking apart. I'll just keep looking until I find them.

Jack10525 said:

Hey thanks for the reply. I didn't find that one and have been searching the net for the last week. It's not a bad guide but is not specific enough. There are some screws or fasteners I can not find on the g5 I am taking apart. I'll just keep looking until I find them.

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Yeah...I know that the link I provided was not that detailed...but it sounded like everything was "fairly" straight forward.

I'm not sure at what point of the disassembly you're at...but are you sure that you have removed everything you can? Maybe something needs to be removed to expose some fasteners below or underneath it.

Good luck,

- Nick

what does the logic board do and how do I know if my computer has a bad/dead one?

BluesForDan said:

what does the logic board do and how do I know if my computer has a bad/dead one?

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The first question(s) would be...Do you have a "dead" computer?, and if so what is it or is it not doing?

- Nick

Hey Nick,

I got it apart!!!! Ok all the easy stuff comes out no problem: graphics card, fans, wind deflector, cpu covers. Once the cpu cover is off you see the huge heat sinks hiding the processor(s). There are 4-6 hex head screws that secure each heat sink(I have 2 heat sinks). The screws are well recessed so I needed a very long allen wrench. Once I got the screws out the heat sink pops off the board. Here is the scarry part. The cpu is permanently attached to the heat sink I think I read somewhere if the cpu is removed from the board a calibration would be necessary when reinstalling. Not sure what that means. After the cpu's are off the board. I still had to remove about 8 screws that hold the board down and about 10-12 anchors that hold the cpu/heat sinks in. After that and every cable is disconnected from the board it should come out. But it is not that easy. The logic board has notches that keep the board secure even with all the screw removed. You have to kinda of pry it off very gently. There really is very little room to move around and the board is quite large compared to a pc board. Well I got it out but am not sure I would be able to put it back together in working condition. Not sure about spending 400 for a board and breaking it putting it in. Any idea if the cpu's indeed need to calibrated if removed from the logic board?

how did you get the power supply cover off?

Jack10525 said:

I got it apart!!!!

Once the cpu cover is off you see the huge heat sinks hiding the processor(s). There are 4-6 hex head screws that secure each heat sink(I have 2 heat sinks). The screws are well recessed so I needed a very long allen wrench. Once I got the screws out the heat sink pops off the board. Here is the scarry part. The cpu is permanently attached to the heat sink I think I read somewhere if the cpu is removed from the board a calibration would be necessary when reinstalling.

Not sure about spending 400 for a board and breaking it putting it in. Any idea if the cpu's indeed need to calibrated if removed from the logic board?

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Congratulations on getting everything apart. Yes to remove those large CPU heat sinks you needed a long-handled (T-handle) allen wrench (it may be a Torx wrench)...it's somewhat similar on the Mac Pro's.

Here's another link about replacing a G5 motherboard...it doesn't say anything about needed to do any sort of recalibration. If you read something about needing to do a calibration, can you attach a link?

How to Replace G5 Motherboards | eHow.com

As far as the cpu "daughtercard" & heat sink being attached...I'm not sure exactly which model G5 you have...but it probably looks something like this:



Regarding the logic board replacement. If you're sure that it needs to be replaced...and you already have everything apart...you might as well do it!

Hope this helps...good luck with the rest of the project,

- Nick

BluesForDan said:

how did you get the power supply cover off?

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Hey Dan,

The power supply has a cover on it that faces the logic board. It has 2 screws that hold it on accessible from inside the case. There are also 4 screws on the bottom of the case that hold the power supply in. Remove them and you can get the ps out. Good luck.

pigoo3 said:

Congratulations on getting everything apart. Yes to remove those large CPU heat sinks you needed a long-handled (T-handle) allen wrench (it may be a Torx wrench)...it's somewhat similar on the Mac Pro's.

Here's another link about replacing a G5 motherboard...it doesn't say anything about needed to do any sort of recalibration. If you read something about needing to do a calibration, can you attach a link?

How to Replace G5 Motherboards | eHow.com

As far as the cpu "daughtercard" & heat sink being attached...I'm not sure exactly which model G5 you have...but it probably looks something like this:

Regarding the logic board replacement. If you're sure that it needs to be replaced...and you already have everything apart...you might as well do it!

Hope this helps...good luck with the rest of the project,

- Nick

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Hey nick,

Yep that is pretty much what the processors look like. I have been watching ebay and found a board on there for 250 shipped. I emailed the seller to see if it would be compatible. I just might do it. We'll see. It's only money right?
PS: I am not sure where I saw the thread about recal'ing the processors. I have been searching the net like crazy.

Jack10525 said:

Hey nick,

Yep that is pretty much what the processors look like. I have been watching ebay and found a board on there for 250 shipped. I emailed the seller to see if it would be compatible. I just might do it. We'll see. It's only money right?
PS: I am not sure where I saw the thread about recal'ing the processors. I have been searching the net like crazy.

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When you say "a board" on e-Bay, do you mean a logic board or are you talking about the 2.0 ghz replacement dual processors?

I thought that your project was to swap your dual 1.8ghz CPU's for a set of 2.0 ghz processors.

As far as the $250 price. I've been watching e-Bay, and I've seen several complete dual 2.0ghz G5 computers sell for less than $250. So basically, if you're willing to spend $250...forget about swapping the processors, and just buy the whole computer for under $250.

Hope this helps,

- Nick