Add Memory slots to 2005 PM G5

The-Pro

macrumors 65816
Original poster
Dec 2, 2010
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Good morning everybody :)

I have just purchased a 2005 dual 2Ghz PowerMac G5 as a temporary replacement for my G4 MDD. I have looked at the insides a little bit and saw that it only has 4 memory sockets. However above and bellow the two pairs of sockets there are the holes and numbering for another 4 memory slots. Now the dual 2.3 GHz 2005 G5 had 8 memory slots and im guessing they just fitted more sockets onto the same logic board.
My question is, it is possible to take the memory sockets out of a G5 and stick them into mine. I dont know how they are fixed, soldered, etc. but it lookes like they just fit in. I can see that the pins come out on the other side of the logic board (of the existing sockets), they dont seem to be soldered. I doubt the two 2.0GHz G5 CPU's each have a 2GB memory limit as the 2004 DP 2.0GHz was able to support 8GB all together over 8 slots.
Has anyone ever done or tried this. I'd be very happy if I could get more then 4GB RAM into the G5.

Cheers, thank you :)

1st pic: holes for memory sockets under the bottom ram slots (bit dusty :D )
2nd pic: hard to see on this pic (the best I could make) but single pins coming out the back of the logic board.
 

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Bug-Creator

macrumors 6502a
May 30, 2011
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There were 2 different 2x2.0GHz G5 PMac (3 if you count the one with the single dualcore 970MP).

The 2.3 Dual-CPU has PCI-X slots and so has one of the 2.0 Dual-CPU models. Bothe feature 8 sockets for max 8GB RAM.

There is also a "pure" PCI model with has only 4 slots for 4GB max (like all other PCI models).

So one has to ask wether your 2x2.0 even has the same mobo as the 2x2.3 (if so one should also be able to replace the PCI-slots with PCI-X ones ??) ?

But even if you could just solder in those xtra RAM-sockets, don't be suprised if you end up with a non-working G5 afterwards as such an upgrade may require additional work on the mobo maybe even slightly different revisions of major chips like the northbridge. Also don't be suprised if the OF or even OSX refuses to cooperate with such a hack...
 

The-Pro

macrumors 65816
Original poster
Dec 2, 2010
1,449
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Germany
There were 2 different 2x2.0GHz G5 PMac (3 if you count the one with the single dualcore 970MP).

The 2.3 Dual-CPU has PCI-X slots and so has one of the 2.0 Dual-CPU models. Bothe feature 8 sockets for max 8GB RAM.

There is also a "pure" PCI model with has only 4 slots for 4GB max (like all other PCI models).

So one has to ask wether your 2x2.0 even has the same mobo as the 2x2.3 (if so one should also be able to replace the PCI-slots with PCI-X ones ??) ?
Interesting thank you.

Well its definitely the early 2005 model (apple Serial number check revealed this) with the PowerPC 970fx (according to MacTracker) MacTracker also says it has 3 33MHz 64-bit PCI slots, and not any PCI-X. So its not the same mobo as the 2.3 and not the same as the 2004 2.0 either, as that one had PCI-X aswell.
The processor in the 2004 dual 2.0 seems to be the same PowerPC 970fx. The benchmarks are about exactly the same for the 2005 and 2004 2.0GHz dual.
All the models that dont have PCI-X slots also only had 4 RAM slots. Thats how it seems to be. But then why would the RAM slot holes for 8 sockets be in the motherboard of the "pure" PCI models.
But even if you could just solder in those xtra RAM-sockets, don't be suprised if you end up with a non-working G5 afterwards as such an upgrade may require additional work on the mobo maybe even slightly different revisions of major chips like the northbridge. Also don't be suprised if the OF or even OSX refuses to cooperate with such a hack...
You see thats what I was wondering. Are there any detailed technical informations on all of the chips in PM G5's out there that you know of?
Im tempted to try it but not so sure. Only if I know that apple just hasn't built more RAM slots into a machine that can use more.
What do you mean by the OF?
 
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Bug-Creator

macrumors 6502a
May 30, 2011
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OF = OpenFirmware

Apple is known to put restrictions in there as for example both the G4 iBook and the G5 iMac have the HW to support dual display but have their external mini-VGA connector limited to mirroring the main display (this restriction can easily be removed by 3rd party SW).

If I was in your place (I'm not, my G5PMac is 2x2.3 :p ) I'd either live with those 4GB (only 2.5 in my G5) or see if I can sell the current one and get a better one for a fistfull of $ ......
 

The-Pro

macrumors 65816
Original poster
Dec 2, 2010
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Germany
Good point. I managed to get this one really cheaply and its in perfect condition etc. Ill keep it and live with 4. Its fine until i get a a new mini as a proper replacement.

I will carry on searching for answers, one never knows. I wouldn't be surprised at all if apple limited the firmware aswell.
Thank you very much :)

Any other information from someone would be greatly appreciated :)
 

666sheep

macrumors 68040
Dec 7, 2009
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It would be interesting to see such mod working. But I'm afraid that 4 slot logic board lacks not only these slots but also other related to them components (i.e. resistors etc). They would need to be installed too.
I bet that firmware wouldn't be the problem and other components such as northbridge etc are exactly the same in 8 slot and 4 slot boards - there was no need to complicate manufacturing process.
 

The-Pro

macrumors 65816
Original poster
Dec 2, 2010
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It would be interesting to see such mod working. But I'm afraid that 4 slot logic board lacks not only these slots but also other related to them components (i.e. resistors etc). They would need to be installed too.
I bet that firmware wouldn't be the problem and other components such as northbridge etc are exactly the same in 8 slot and 4 slot boards - there was no need to complicate manufacturing process.
I was thinking more about all the resistors and connectors aswell.
It increases manufacturing costs significantly if extra chips would need to be designed or bought.
Lets say if I were to look at a logic board from an 8 slot and one from 4 slot, and all the resistors etc. are the same, would that be "proof" enough that the only thing missing are the physical slots themselves?
Ive been looking for detailed photos of 8 slot and 4 slot motherboards but I cant seem to find any.
 
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666sheep

macrumors 68040
Dec 7, 2009
3,623
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Poland
Lets say if I were to look at a logic board from an 8 slot and one from 4 slot, and all the resistors etc. are the same, would that be "proof" enough that the only thing missing are the physical slots themselves?
I'd call it circumstantial evidence rather than proof ;)
There's a MR member who might shed some light on this case. He has schematics of G5 logic boards IIRC and some experience in re-soldering G5 RAM slots.
Try to ask him or maybe invite to post in this thread if possible.
 

The-Pro

macrumors 65816
Original poster
Dec 2, 2010
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Germany
I'd call it circumstantial evidence rather than proof ;)
There's a MR member who might shed some light on this case. He has schematics of G5 logic boards IIRC and some experience in re-soldering G5 RAM slots.
Try to ask him or maybe invite to post in this thread if possible.
Thanks mate :)
I have contacted the member. I hope he responds here, from what you said it seems like he knows stuff around this topic.
 

LeoTheLion89

macrumors 6502
Feb 14, 2012
353
0
OF = OpenFirmware

Apple is known to put restrictions in there as for example both the G4 iBook and the G5 iMac have the HW to support dual display but have their external mini-VGA connector limited to mirroring the main display (this restriction can easily be removed by 3rd party SW).

If I was in your place (I'm not, my G5PMac is 2x2.3 :p ) I'd either live with those 4GB (only 2.5 in my G5) or see if I can sell the current one and get a better one for a fistfull of $ ......
may be off topic but is related to the post can you tell me the SW needed to remove the restriction of Dual Displays on a eMac?
 

The-Pro

macrumors 65816
Original poster
Dec 2, 2010
1,449
35
Germany
well I can pick up a broken G5 motherboard for 1€ :D
I will have plenty of RAM slots to play with then, its the one with 8
Its a pity no one else knows anything about this :(
 
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