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Bad RAM on PowerMac G5 - Interpreting POST

4701 Views 5 Replies Latest reply: Apr 14, 2009 10:40 AM by grisou-403 RSS
grisou-403 Calculating status...
Currently Being Moderated
Nov 26, 2006 7:48 PM
I have a problem with RAM DDR400 on a PowerMac G5 2x2 GHz (July 2004 model with 8 DIMM slots) equipped with 4 x 256 Mo and 2 x 512 Mo SDRAM all installed in pairs by the vendor .

Recently, after updating to OSX Tiger - 10.4.7 or 8 - I discover that the 4 x 256 Mo memory items are well recognized by OSX - according to "About this Mac" and "System Infos" - but not the 2 x 512 Mo SDRAM...!!! So, my G5 showed I only had 1 Go RAM instead of 2 Go. And I guess it used only 1 Go.

I tried everything from Tiger clean install to disk repair, PRAM reset, etc ... with no effect at all on the "missing" RAM's recognition by OSX.

Then I ran the "Apple Hardware Test" software (CD v.2.2.4). It shows - in red alert - the two 512 Mo DIMMs as "0-512 Mo" RAM (instead of 512 Mo fit) with one indicated as "failed POST". Then the quick test comments this failed DIMM5 (J42) with the following error message : "post/0/2048"...!!!

Did somebody knows what the Power-on Self Test (POST) "0/2048" error exactly means ??

Is there somewhere a kind of "list" referencing POST errors ?

Initially the 2 Go RAM were fully recognized by Panther 10.3.8 (cf. "System Infos") with the G5 firmware 5.1.8f2. However, when upgrading to Tiger (10.4.0), I also updated my G5 firmware with 5.1.8f7 (as recommended for June 2004 PowerMac G5).

Is it possible that the G5 firmware update "damaged" or "changed" something related to the RAM's access by OSX Tiger ?

Any help or suggestion will be welcomed. Thanks in advance.

Grisou403 - from Paris, France

PowerMac G5 2x2 GHz   Mac OS X (10.4.8)  
  • maclover Level 4 Level 4 (3,855 points)
    Currently Being Moderated
    Nov 27, 2006 3:34 AM (in response to grisou-403)
    Hi grisou403, and a Warm Welcome to Apple Discussions and the Power Mac G5 Forum!

    Well, whether it's caused by the firmware update(always a delicate process), 10.4 (OS X seems to get more picky about RAM with each successive update) or by something else - you could try re-seating the RAM, or swapping slots with the RAM that is recognised. Instructions are here

    G5 RAM specs. are here

    Slot locations are here.

    There is a more comprehensive RAM test - Memtest

    and User Interface to Memtest - Rember

    The precise meaning of "post/0/2048" is probably: "call AppleCare" or "call the place where you bought the RAM" - but try the re-seating, etc. first. Good Luck.
  • DaddyPaycheck Level 6 Level 6 (16,035 points)
    Currently Being Moderated
    Nov 27, 2006 3:41 AM (in response to grisou-403)

    Greetings and welcome.

    It is possible that the OSX update caused the system to be more selective about the memory that it is using. Each update of OSX seems to cause memory problems. Unless you specifically updated the firmware, none would have been done through the normal course of updating OSX.

    Try reseating the RAM. Sometimes that will fix it. If not, did it come with a warranty? Many vendors sell RAM with a lifetime warranty. It is best to avoid those who donnot offer such a warranty.

    I don't know of any comprehensive list of POST errors.


    Basement XServe sitting on a Box of Apples, Mac OS X (10.4.8), A collection of clinking, clanking caliginous junk.
  • maclover Level 4 Level 4 (3,855 points)
    Hi grisou-403 - Thank you for the detailed feedback. It's very helpful to know what happened, what you did, what worked, what didn't - especially from someone who is obviously careful and methodical in their problem-solving.

    Glad it's fixed - Thanks for taking the time to post such a comprehensive analysis. Good Luck! And Merry Christmas!


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