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Faulty Ram Question

3778 Views 9 Replies Latest reply: Jul 8, 2010 3:44 PM by mhollis RSS
Alex Taylor Calculating status...
Currently Being Moderated
Jun 22, 2010 1:39 AM
Hi there I have a Mac Pro Dual Core Xeon 2.66 GHz and I am supposed to have 4GB of ram, 4 x 512MB
in Riser A and 2 x 1GB in Riser B, DIMM 1 & 2.

Recently I've noticed in system profiler it lists as having just 3GB of ram, in the diagnostics power on self-test I get this

Power On Self-Test:

Last Run: 22/06/10 6:11 PM
Result: Failed
Failure Type: Memory
Memory Slot: DIMM 2/DIMM Riser B

When I check memory it lists all the ram as being 512 MB with an OK status.

Now I know for sure the Ram in DIMM2/DIMM Riser B must be faulty as I tried swapping them around and it listed the swapped module placing as failed. My question is, why does it list the ram as being only 512MB when the two bottom are 1GB, does the good stick of 1GB ram spread itself out to act as 512MB? Or is this a sign of another stick that is failing?

Lately my whole system has been slowing down majorly, spinning beachballs galore, force quits happening constantly and I'm hoping by replacing the ram it will solve the many frustrating problems.

Thanking you for any info.

PS I have run several test with rember and it always comes up as passed...
Mac Pro Dual 2.66 4 GB Ram 2 X 500GB HD Hitachi & WD 2 X Super Drive 30" Display, Mac OS X (10.6.4), 2 x Pioneer DVR-111D Macbook Pro 2.66 500 GB 7,200 4 gb ram
  • The hatter Level 9 Level 9 (58,600 points)
    Currently Being Moderated
    Jun 22, 2010 3:23 AM (in response to Alex Taylor)
    Ditch it, RMA it, but replace it.
    Mac Pro 8800GT 10.6.4 /, Windows 7, Core i7 3.2GHz / GTX 260 / 10K VelociRaptors
  • CloGram Level 1 Level 1 (5 points)
    Currently Being Moderated
    Jun 22, 2010 11:29 AM (in response to Alex Taylor)
    My problem is that while adding RAM, the bottom (riser B) stopped showing up at all.
    It's possible that it wasn't showing up before the new RAM, but I failed to check beforehand.
    So - either way, I wonder how to resolve this. I'd hate to have to get a whole new unit for the DIMM bank!

    I originally had four 1GB DIMMs (in Riser A & B, slots 1 & 2); then added two 4GB DIMMs (from Crucial). I first added the new ones to Riser A (as recommended), but as Riser B showed all empty, I've tried moving them all around. Riser B never shows up.
    The most current config I have shows the following:
    Riser A: DIMM 1: 4GB
    Riser A: DIMM 2: 4GB
    Riser A: DIMM 3: 1 GB
    Riser A: DIMM 4: 1 GB
    Riser B: DIMM 1: empty
    Riser B: DIMM 2: empty
    Riser B: DIMM 3: empty
    Riser B: DIMM 4: empty

    I've tried again & again to reseat the Riser to no avail. I'm hoping someone will tell me I just have to reset something I missed, as I hope not to have to replace the whole "riser" unit! yikes!
    MacPro1,1 (Intel Xeon), Mac OS X (10.5.8)
  • The hatter Level 9 Level 9 (58,600 points)
    Currently Being Moderated
    Jun 22, 2010 1:57 PM (in response to CloGram)
    Run AHT.

    Try to get Apple to send out new Riser

    Try a new pair of DIMMs.

    When buying new RAM, test with JUST the new RAM before mixing both.
    Mac Pro 8800GT 10.6.4 /, Windows 7, Core i7 3.2GHz / GTX 260 / 10K VelociRaptors
  • sprout Level 1 Level 1 (40 points)
    Currently Being Moderated
    Jun 22, 2010 2:03 PM (in response to Alex Taylor)
    I'm assuming you've swapped the position of the two risers as well - if not, definitely try that. Not so much to resolve the issues, but to isolate it to either the riser or the MLB. Riser is easy for you to swap out; MLB - not so much
    Apple //gs
  • CloGram Level 1 Level 1 (5 points)
    Currently Being Moderated
    Jun 23, 2010 9:08 AM (in response to sprout)
    Thx. Did all above swappings mentioned. I'll try the AHT, but it's looking like the logic board-- but I'll remain hopeful.
    I'll report back if I have any aha's or lucky breaks!
    Thanks folks!
  • CloGram Level 1 Level 1 (5 points)
    Currently Being Moderated
    Jun 23, 2010 9:09 AM (in response to CloGram)
    Hope y'all can laugh at this one (I did... laugh of relief!)...

    Yes, I'd done all the combinations of RAM/risers/DIMM slots possible; called my favorite authorized Mac repair guys (who said if I'd actually done all that - it's most likely time to replace the logic board-yikes$$!; was prepping to do AHT as soon as I'd started up again (after one last try to seat the unrecognized Riser)...

    This time, I used a flashlight and, lo and behold, saw that there was a kind of label (attached to a wire) that had been in the way, and jamming itself into the port where the Riser-pins need connection. (Should have used a flashlight the first time).

    (sorry my techno-lingo is so shabby).

    So - I want to thank all those posting ideas to help me. I always learn so much!
  • mhollis Level 1 Level 1 (10 points)
    Currently Being Moderated
    Jul 8, 2010 2:13 PM (in response to CloGram)
    So, let me get this straight:

    CloGram *successfully mixed 1GB DIMMs and 4GB DIMMs* and they worked (once he figured out the wire-blocking label trick). This is despite the fact that Mac RAM Direct: http://macramdirect.com/macpro.html is saying:

    Mac RAM Direct wrote:
    note: MacPro firmware prefers not mixing 4GB with other modules


    (Go ahead, take a look at their website. They say it in red letters.)

    Does anyone know if this is true for the 2009 Mac Pro Dual Quad Core Macs?
    Mac Pro Cheese Grater with double the cheese., Mac OS X (10.5.8), iPhone 1.12
  • The hatter Level 9 Level 9 (58,600 points)
    Currently Being Moderated
    Jul 8, 2010 2:44 PM (in response to mhollis)
    Maybe if some were more conversant and realized what MacPro1,1 means then the discussion wouldn't go off on false directions and mis-leading info.

    4GB DIMMs applies ONLY to 2009 (DDR3).

    RAMjet is a well respected name of Mac Pro memory and has the same warning, as does MacSales, and they both will not certify using their DDR3 4GB in such a mix.

    Pairs of any size and mix work just fine in pre-2009, which use different FB-DIMMs.
    Mac Pro 8800GT 10.6.4 /, Windows 7, Core i7 3.2GHz / GTX 260 / 10K VelociRaptors
  • mhollis Level 1 Level 1 (10 points)
    Currently Being Moderated
    Jul 8, 2010 3:44 PM (in response to The hatter)
    Uh oh...

    I just bought a 16GB kit. And *Crucial are saying that it's perfectly OK to mix and match*. Go ahead and ask them. Here is the conversation I had with their representative:

    Crucial On-line Support:
    Hello, my name is Jennie . How may I help you?
    Mark Hollis: Hi, Jennie, I can see you are taking a lot of calls, so I shall be brief.
    Mark Hollis: I am having trouble selecting RAM for my Mac Pro (2009 dual-quad-core Intel Nehalem running at 2.93GHz). I have 8 GB of RAM, consisting of 2GB DDR3 ECC modules.
    Mark Hollis: I have been told elsewhere that MacPro firmware prefers not mixing 4GB with other modules, yet your website seems to make no mention of this.
    Mark Hollis: So I downloaded your Crucial MacScanner. Ran it. It sends me to a page that says "click here" to see what we recommend. I get an error page.
    Mark Hollis: Is this issue about the firmware correct?
    Jennie : I have not heard this.
    Mark Hollis: I would like to be able to eventually max out the amount of RAM in my system but I'd also like to not throw away RAM.
    Mark Hollis: Can you find out?
    Mark Hollis: And can you have Crucial correct the problem with the scanner? Jennie : Just asked Tech level 2 and he confirms that this is not any thing that he has heard also. So no it is not correct.
    Jennie : I will ask that the scanner issue be looked into.
    Jennie : Is there anything else I can assist you with?
    Mark Hollis: OK, cool! So Tech level 2 says they have had no problems with RAM when mixing 2GB and 4GB modules.
    Jennie : That is correct.
    Mark Hollis: And Crucial has tested this and Apple says this is OK.
    Jennie : No
    Jennie : Apple has not said that it is correct either.
    Mark Hollis: No, Crucial has not tested this?
    Jennie : So if we have not been told this by Apple then in our book no it is not true.
    Mark Hollis: Is Apple Mum about this? I'm looking for a positive "we test this config all of the time with no problems.
    Jennie : Have you spoke with Apple about this.
    Jennie : Are you having issues with this.?
    Mark Hollis: I do video editing on my Mac Pro and cannot afford downtime.
    Mark Hollis: i have not tested this kind of a configuration myself because testing is not something I am inclined to do.
    Jennie : Tech level 2 and he confirms that this is not any thing that he has heard also. So no it is not correct.
    Mark Hollis: OK, I shall be purchasing within the week. And Please tell Tech level 2 that I shall make him personally responsible for video problems (not serious).
    Mark Hollis: I do video editing on my Mac Pro and cannot afford downtime.
    Mark Hollis: i have not tested this kind of a configuration myself because testing is not something I am inclined to do.
    Jennie : Will do.


    I have always had the utmost respect for Crucial until this conversation, if what you are saying is correct, hatter. Obviously they're using a "book" which may not be updated to show specs on MacPro 1,1. And I'll just bet her name is not "Jennie" but Amrita, doing the night shift in Bengal.

    So it looks like I'll be taking out (and wasting) 8GB of system RAM in my Mac Pro to only double the amount of RAM I have in the system.
    Mac Pro Cheese Grater with double the cheese., Mac OS X (10.5.8), iPhone 1.12

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