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iMac G4 not recongnizing RAM

i have a 2003 model iMac G4 with a 1GHz processor and i tried to put a 512 MB stick of ram in it and when i turn it on it still boots into leopard suprisingly but it says it only has 256MB of ram. This iMac used to have 1.25 GB of ram but i have put the ram into my iBook G4 because i use it for school and the 512 stick came from the iBook. Do these machines use diffrent ram?

iMac G4-OTHER, Mac OS X (10.5.8), 2003 Model

Posted on Apr 13, 2016 12:06 PM

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Question marked as Best reply

Posted on Apr 14, 2016 5:13 AM

Can you identify the iBook G4? There were several different builds across the years

the G4 was manufactured; the first models all use PC2100 DDR266 200-PIN SO-DIMM.


Only the last iBook G4 12-in + 14-in from Mid 2005 use the PC2700 DDR333 200-pin

SO-DIMM; and this chip is the same one that matches the iMac G4 USB2.0 user upgrade

slot specification.


There were two models iMac G4 with 1.0GHz processor; one uses PC2100 DDR266 200-

pin SO-DIMM while the later model uses PC2700 DDR333 200-pin SO-DIMM chips...


Some models can use the later spec RAM chip (at slower original memory speed due to

limits on the computer hardware) so the DDR333 is seen as DDR266 in older Mac G4s.

A DDR266 SO-DIMM from an older iMac G4 probably won't work in later model iBook G4.


I have a Mid-2005 iBook 12-inch 1.33GHz model that can use the same upgrade RAM chip

the last models USB2.0 iMac G4 (PC-2700 DDR333 200-pin SO-DIMM) in a direct swap.

And I have a few of these iMac G4 1.25GHz models. The factory RAM chip is a different spec

and pin count, and requires special take apart ritual to upgrade to higher capacity.


You could swap the chips back to where they came from to test and see if they both are OK.

If you touched the metal contacts on the RAM, that may have shorted the chips; or the RAM

was not seated fully (if the parts were correct in the first place.)


And you may have to reset the PMU in the iMac G4 to see if the change in RAM is recognized

Resetting the iMac (Flat Panel) Power Management Unit (PMU) - Apple Support


As a last resort; this reset could deplete the PRAM battery if not done correctly. And in order

to replace the clock battery, a major takeapart is required. Enough effort to also consider an

upgrade of the factory slot RAM. Thermal paste, extra tools, & careful handling are required.


Mr Totes iMac G4 (USB2.0) Take apart:

http://www.mrtotes.co.uk/page1/page1.html


iMac G4 Take-apart for Drive, RAM, battery:

http://www.xlr8yourmac.com/systems/imac_g4/imacg4_takeapart.html


This has been a difficult reply to formulate and I've written this perhaps four times, with details.

The everymac.com site & a download of mactracker.ca (for offline database) are recommended.


Since the time here is now approaching 1:40AM (AKDT) I'm going offline now.

Good luck & happy computing! 🙂

3 replies
Question marked as Best reply

Apr 14, 2016 5:13 AM in response to Tristris389

Can you identify the iBook G4? There were several different builds across the years

the G4 was manufactured; the first models all use PC2100 DDR266 200-PIN SO-DIMM.


Only the last iBook G4 12-in + 14-in from Mid 2005 use the PC2700 DDR333 200-pin

SO-DIMM; and this chip is the same one that matches the iMac G4 USB2.0 user upgrade

slot specification.


There were two models iMac G4 with 1.0GHz processor; one uses PC2100 DDR266 200-

pin SO-DIMM while the later model uses PC2700 DDR333 200-pin SO-DIMM chips...


Some models can use the later spec RAM chip (at slower original memory speed due to

limits on the computer hardware) so the DDR333 is seen as DDR266 in older Mac G4s.

A DDR266 SO-DIMM from an older iMac G4 probably won't work in later model iBook G4.


I have a Mid-2005 iBook 12-inch 1.33GHz model that can use the same upgrade RAM chip

the last models USB2.0 iMac G4 (PC-2700 DDR333 200-pin SO-DIMM) in a direct swap.

And I have a few of these iMac G4 1.25GHz models. The factory RAM chip is a different spec

and pin count, and requires special take apart ritual to upgrade to higher capacity.


You could swap the chips back to where they came from to test and see if they both are OK.

If you touched the metal contacts on the RAM, that may have shorted the chips; or the RAM

was not seated fully (if the parts were correct in the first place.)


And you may have to reset the PMU in the iMac G4 to see if the change in RAM is recognized

Resetting the iMac (Flat Panel) Power Management Unit (PMU) - Apple Support


As a last resort; this reset could deplete the PRAM battery if not done correctly. And in order

to replace the clock battery, a major takeapart is required. Enough effort to also consider an

upgrade of the factory slot RAM. Thermal paste, extra tools, & careful handling are required.


Mr Totes iMac G4 (USB2.0) Take apart:

http://www.mrtotes.co.uk/page1/page1.html


iMac G4 Take-apart for Drive, RAM, battery:

http://www.xlr8yourmac.com/systems/imac_g4/imacg4_takeapart.html


This has been a difficult reply to formulate and I've written this perhaps four times, with details.

The everymac.com site & a download of mactracker.ca (for offline database) are recommended.


Since the time here is now approaching 1:40AM (AKDT) I'm going offline now.

Good luck & happy computing! 🙂

Apr 14, 2016 2:00 PM in response to Tristris389

The spec of the iMac G4 would have, since the issue could relate to the RAM not being

correct to the application; or damaged in the process of handling, or reinstalling, etc.


I'd made another extensive reply to this topic again, but chose instead to delete it.

Check the RAM, to be sure the failed item is properly seated. That nothing like dust

is in the slot where the memory chip needs to fit (with a snap) down into the channel.


And as suggested, if you have detailed information or need some, check everymac.com

plus get & use the database app from MacTracker.ca for offline use. All technical specs

are available from these sources, as are upgrade specs and supported config information.


Good luck & happy computing! 🙂

iMac G4 not recongnizing RAM

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