Mac Pro Memory Configuration Weirdness

Discussion in 'Mac Pro' started by bensim, Feb 13, 2008.

  1. bensim macrumors newbie

    Joined:
    Jan 15, 2004
    Location:
    Denver, CO
    #1
    My experience is similar to another thread (http://forums.macrumors.com/showthread.php?t=433946), but I think it is different enough to merit a new thread.

    I purchased two sticks of 1gb RAM for my Early 2008 3.0 mac pro from Crucial. I installed them the way that Apple suggested:

    A1: Apple 1gb
    A2: Apple 1gb
    B1: Crucial 1gb
    B2: Crucial 1gb

    The computer did not recognize the RAM in the B riser, giving me only 2gb total. Under "Diagnostics" in the System Profiler, it said under "Power on Self-Test" that the RAM in riser B had failed.

    So I switched the risers with a similar result. It still only recognized the Apple RAM which was now in the B riser.

    I called Crucial. I was instructed to put the Crucial RAM in stock config:

    A1: Crucial 1gb
    B1: Crucial 1gb

    It worked so I said thanks and goodbye. However, I noticed that when I moved windows around, they moved in a very jerky way. It was obvious. The cause of this could be so many things that I didn't check... But I decided to put the Apple RAM back in the stock config and totally remove the Crucial RAM. It worked and the windows didn't jerk when moved.

    I ran an Xbench 1.3 test and saved it. And then I did the following config:

    A1: Apple 1gb
    A2: Crucial 1gb
    B1: Apple 1gb
    B2: Crucial 1gb

    This is not what Apple shows in the manual, but it worked. I had 4gb of RAM. And the windows moved without jerking. Xbench gave me faster results.

    I apologize for this being so long-winded, but I wanted to tell what I did as accurately as I could. Hopefully this explanation serves some useful purpose to someone. I do have some questions, though:

    1. Does this sound right?

    2. Should I be concerned about the Crucial memory? In the Apple System Profiler the Crucial RAM shows up as 800 MHz, so it seems as though it's the correct RAM.

    Thanks for listening.
     
  2. newtech macrumors 6502

    Joined:
    Jun 2, 2007
  3. bensim thread starter macrumors newbie

    Joined:
    Jan 15, 2004
    Location:
    Denver, CO
    #3
    Good question! It's my OCD kicking in!

    Seriously, it just seems weird to me that that Apple recommended config did not work. I did it the "Crucial way" on my old dual G5, so that gives me some comfort.

    On a side note, this new computer boots ridiculously fast. It made all my swapping and testing very easy!
     
  4. XianPalin macrumors 6502

    XianPalin

    Joined:
    May 26, 2006
    #4
    His situation would worry me.
     
  5. deathshrub macrumors 6502

    Joined:
    Oct 30, 2007
    Location:
    Christmas Island
    #5
    The crucial RAM you ordered is DEFECTIVE. If crucial has a lifetime replacement guarantee, call and say your RAM is defective and you want a replacement. Don't say too much other than "I have tried the system with only the crucial RAM in and either windows freeze or the system doesn't boot." Don't let them talk you out of it either, their ram is f*cked and you absolutely deserve it replaced.

    Hope everything goes well for you.
     
  6. barijazz macrumors 6502

    Joined:
    Dec 29, 2007
    #6
    seconded.
     
  7. Banacek macrumors 6502

    Joined:
    Jan 13, 2008
    #7
    Thirded :)
     
  8. barefeats macrumors 65816

    barefeats

    Joined:
    Jul 6, 2000
    #8
    "A1: Apple 1gb
    A2: Crucial 1gb
    B1: Apple 1gb
    B2: Crucial 1gb"

    That's right.
     
  9. Banacek macrumors 6502

    Joined:
    Jan 13, 2008
    #9
  10. deathshrub macrumors 6502

    Joined:
    Oct 30, 2007
    Location:
    Christmas Island
    #10
    No, it isn't. Please don't spread FUD or give advice when you don't know what you're talking about, you will mess someone else's machine up.

    Banacek, that OWC guide you posted is absolutely correct. I'm not sure why Apple decided to go with A1, B1 for the default RAM configuration, it's definitely more confusing than it was with the last two revisions.
     
  11. Canoehead2 macrumors newbie

    Joined:
    Jan 29, 2008
    #11
    In theory, both ways should work since they are all 1GB - but it sounds like the Crucial RAM is ****ed - get rid of it.
     
  12. deathshrub macrumors 6502

    Joined:
    Oct 30, 2007
    Location:
    Christmas Island
    #12
    RAM are supposed to be installed in matched pairs from the same vendor. In that case, A1 and A2 will be filled with Apple and (malfunctioning) Crucial RAM which is likely from a different vendor/batch/whatever.
     
  13. Banacek macrumors 6502

    Joined:
    Jan 13, 2008
    #13
    Yeah, I was planning on following that guide that OWC had. Thanks!
     
  14. bensim thread starter macrumors newbie

    Joined:
    Jan 15, 2004
    Location:
    Denver, CO
    #14
    Thanks for all of the replies -- I really appreciate it. I'm going to return the RAM and seek a different route.
     
  15. tugger macrumors regular

    tugger

    Joined:
    Apr 14, 2005
    Location:
    KTLH
    #15
    You're getting sliced and diced on price at Crucial. 2x1GB for $319???? You can get 2x2GB chips at OWC (macsales.com) for $219.

    I installed my memory like this:

    A1: OWC 2GB
    A2: OWC 2GB

    B1: Apple 1GB
    B2: Apple 1GB

    All memory recognized.
     
  16. Fornothingelse macrumors newbie

    Joined:
    Feb 13, 2008
    #16
    I installed 2 1 gigs in my new mac pro that I ordered from OWC and ran into the same problem. After reading your post I tried the configuration that yours worked with, but no luck. No matter what configuration I try, the machine will only read 2 gigs of memory. Sometimes it will even read 1 apple and 1 OWC because they are on different risers. I decided to send it back and have a try with another set, because the diagnostics keep saying "failed."

    If anyone has any more information on this I would greatly appreciate it.
     
  17. LOZER macrumors member

    Joined:
    Jan 12, 2008
    Location:
    Kalamazoo, MI
    #17
    I personally like Crucial, but it should have worked the suggested way Apple had it. I would return the ram to be safe and get new ones, but if your happy with it keep it by all means, besides they have a lifetime warranty at Crucial. The OWC configuration is 100% correct, thats what the Mac Pro manual states and the way i set up my OWC ram as well.
     
  18. djjclark macrumors regular

    Joined:
    Feb 17, 2008
    #18
    Did the new ram fix your problem? I am seeing something very similar. No matter where I place my memory (2 1gb apple and 2 1 gb OWC) I can only see 2 gb total and sometimes only 1gb. When running the hardware test it says everything is fine but it lists serial numbers for the apple ram but not the OWC.
     
  19. bigbird macrumors 6502

    Joined:
    Aug 17, 2007
    Location:
    Canada
    #19
    That's the sign that only one of your two OWC sticks is bad. Remember that these FB-DIMM's must be installed in pairs, hopefully matched. If one half of the pair is defective, they both will show up as defective if installed as a pair.
     
  20. bilbo--baggins macrumors 6502a

    Joined:
    Jan 6, 2006
    Location:
    UK
    #20
    I would definitely return the Crucial RAM. Would be worth calling them to discuss it - they need to know if their RAM isn't working correctly when installed according to Apple's instructions. If the memory is faulty, then get replacements and you should be fine. If all Crucial memory does the same they need to stop selling it NOW!

    Both ways should only work if the Apple and the Crucial RAM are all absolutely identical - presumably having said that there is a very slim chance of that.

    I have 4 x 1GB modules at the moment, 2 x 1GB stock Micron RAM in A1 and A2, and 2 x 1GB Hynix RAM (stock ram purchased on ebay) in B1 and B2, and it works fine. I haven't bothered trying them the 'wrong way round', eg. A1 matching B1 and A2 matching B2.

    Question to the OP: what brand is the 'Apple' memory? Most people have been getting Hynix, but mine was Micron which is probably the same/similar to the Crucial memory you have got.
     

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