Suddenly recognizing only 2GB out of my 4GB memory

Discussion in 'Mac Pro' started by rob5, Dec 7, 2006.

  1. rob5 macrumors regular

    Joined:
    Oct 5, 2003
    Location:
    Connecticut
    #1
    Have a 2.66GHz MP with 4GB RAM. I got it last month and it's worked fine. Suddenly today its saying I only have 2GB in 'about' window and only 2x1GB in Riser A / Slot 1 and 2.

    Anyone know what happened to the other two?

    This is all Apple ram by the way, ordered from them.. not third party.
     
  2. R.Youden macrumors 68020

    R.Youden

    Joined:
    Apr 1, 2005
    #2
    No smoke coming from your MacPro? It could be dead. I would check that it is installed properly before you give Apple a ring or go to a store. Maybe try tacking RAM out untill you find the ones that dont work.
     
  3. rob5 thread starter macrumors regular

    Joined:
    Oct 5, 2003
    Location:
    Connecticut
    #3
    thanks ill try when im home. nothing changed though which is weird. the machine never moves
     
  4. Kendall015 macrumors regular

    Joined:
    Sep 12, 2006
    #4
    I would open up the case, take out and reinsert Riser B, start up again, and see if the memory is recognized before you do anything else.
     
  5. rob5 thread starter macrumors regular

    Joined:
    Oct 5, 2003
    Location:
    Connecticut
    #5
    ok, back..

    just took out riser B and reinserted it.. still nothing - only sees riser A / first 2 GB modules in sys prefs..

    anything else i can try? this isn't good.. $800 upgrade and less than 1 1/2 months it stopped working
     
  6. jdechko macrumors 68040

    Joined:
    Jul 1, 2004
    #6
    Have you run the hardware check on it (on one of the CD's)?
     
  7. mklos macrumors 68000

    mklos

    Joined:
    Dec 4, 2002
    Location:
    My house!
    #7
    If you swap the riser cards does it only recognize B (which was A) or not boot at all? I wouldn't see why it would make a difference if A was in B or visa versa. This may narrow down if its a bad risercard. 

    OR 

    take the RAM out of riser card A and put it into riser card B and see what happens. 

    Not really familiar with how the new riser cards work but I'm thinking that maybe one fo the sticks of RAM went bad so its not being recognized at all possibly even making the riser card not appear. RAM can go bad at any time. Doesn't matter whether you paid $50 for it, or $50,000 for it. 

    Basically do a lot of swapping out and switching around, but MAKE SURE you know what was working and what wasn't working. So keep a way of remember what RAM was in riser card A. You know for sure that the RAM in riser card A works. This way you won't accidentally be putting bad RAM into A and then wonder why the computer won't boot at all anymore. 
     
  8. dickmoonpie macrumors newbie

    Joined:
    Dec 7, 2006
    #8
    only 2gb of my 4gb working under XP

    I am having similar issues but only under XP/bootcamp. The system only recognizes 2gb of ram, but in OSX it sees all 4gb?
     
  9. mklos macrumors 68000

    mklos

    Joined:
    Dec 4, 2002
    Location:
    My house!
    #9
    Its probably either a limitation of Boot Camp, and/or a Windows XP limitation. This is not a hardware problem. *
     
  10. dickmoonpie macrumors newbie

    Joined:
    Dec 7, 2006
    #10
    XP supports up to 4gb. Bootcamp should have nothing to do with this. Is it the apple provided driver?
     
  11. rob5 thread starter macrumors regular

    Joined:
    Oct 5, 2003
    Location:
    Connecticut
    #11
    ok, this is really really weird. I just got done testing. it appears that my mac pro can't recognize more than 2GB of ram, and one of my RAM modules is also bad (but removing it doesn't help)..

    here are the combos i've tried. i have 4x1GB:

    Module A1
    Module A2
    Riser A
    ---
    Module B1
    Module B2
    Riser B

    'Module A' will include both A1+A2, and same for B...

    now, here are combos..

    Module A
    Riser B
    works

    Module B
    Riser B
    doesn't work - B1's light on the riser card stays red. so this module appears to be bad

    Module B2
    Riser B
    works. this is without the bad module above

    now since that works, you'd think both modules for A and the one working B would work but ..

    Module A
    Riser A
    ---
    Module B2
    Riser B
    doesn't work - only sees 2GB

    now this is weird.. when i put Module B2 and Riser B in the first slot, and A and riser A in the 2nd, OSX will only recognize the modules in riser B, not the one in A even though the one in A comes up as 1GB without anything in the bottom riser:

    Module B2
    Riser B
    ---
    Module A
    Riser A
    doesnt work

    now i tried mixing them up a bit

    Module B2
    Module A1
    Riser 2
    ---
    Module A2
    Riser A

    only sees the first riser (2GB)

    so aside from the 1 stick that is bad (stays red), i don't get this behavior.. its obvious both riser cards work, and the ram is good.. OSX won't recognize anything over 2GB it seems
     
  12. slughead macrumors 68030

    slughead

    Joined:
    Apr 28, 2004
    #12
    If one of your RAM chips is bad, it will also disable another RAM chip due to the nature of the motherboard

    the mobo only recognizes an EVEN number of chips. Therefore, if you had 4 and one dies, you only have 3.. but 3 is odd so it knocks it down to 2

    Replace the bad chip and you'll find it goes right back to where it was before.
     
  13. rob5 thread starter macrumors regular

    Joined:
    Oct 5, 2003
    Location:
    Connecticut
    #13
    Thank you!

    Is it possible to get the chip replaced at an Apple store to save time - or do I need to have one shipped to me from Apple? It was a BTO ...
     
  14. slughead macrumors 68030

    slughead

    Joined:
    Apr 28, 2004
    #14

    You're f*cked!

    BTO's have to be fixed by Apple's fixeroo shop which exists across the river styx and past the 3 headed marmoset!

    Local stores wont do it.

    My info is a little old, call your local Apple store and ask before mailing that thing to Singapore (or whereever)
     
  15. rob5 thread starter macrumors regular

    Joined:
    Oct 5, 2003
    Location:
    Connecticut
    #15
    Wait, I need to send the whole thing to replace a stick that would take me two seconds to do if they sent it to me?
     
  16. slughead macrumors 68030

    slughead

    Joined:
    Apr 28, 2004
    #16
    You could try and get on Applecare and beg them to just send you the chip.. they usually don't trust customers to diagnose their own machines though.
     

Share This Page