Disappearing RAM on Mac Pro...

hmachmac
Posted:
in Genius Bar edited January 2014
On my Mac Pro 4-core 3ghz, I get different About-This-Mac screens and profiles on different boot-ups. I do have 8 gig of Crucial RAM installed in addition to the 1 gig of Apple RAM the machine came with. I haven't quite figured out what's happening to that particular 2 gig RAM. Seems to disappear randomly, always in DIMM 1 of Riser A, wherein both of the 2 gig DIMMs are read as 1 gig each instead of 2 gigt. I do have Boot Camp set up and running Windows XP, no Parallels on this machine.



The machine runs perfectly. Never had a crash, never had a kernel panic. The problem is always in DIMMs 1 and 2 of Riser A.













Any idea what's happening here?

Comments

  • Reply 1 of 3
    kareliakarelia Posts: 525member
    Try reinstalling Leopard... and if that doesn't work, chances are, you've got bad hardware somewhere.



    Try swapping the affected chips to another set of slots, perhaps trade them with chips B1 and B2. If A1 and A2 continue to have the problem, you've likely got a bad riser. If the problem moves with the chips to B1 and B2, you've likely got bad memory.
  • Reply 2 of 3
    hmachmac Posts: 3member
    Quote:
    Originally Posted by Karelia View Post


    Try reinstalling Leopard... and if that doesn't work, chances are, you've got bad hardware somewhere.



    Try swapping the affected chips to another set of slots, perhaps trade them with chips B1 and B2. If A1 and A2 continue to have the problem, you've likely got a bad riser. If the problem moves with the chips to B1 and B2, you've likely got bad memory.



    Thanks for the reply. Switching the DIMMs around was something I was putting off, but of course is obvious, and probably the first thing I should have done.



    Anyway, I did swap DIMMS from slots A1 and A2 with B1 and B2 and now, so far, it's back to 9 gig RAM total. Not sure if it's defective RAM, defective riser/bus, or that the DIMMs and/or risers just needed re-seating. We'll see. If it drops back to 7 gig at some point, I guess I'll know by looking at which riser is mis-reading the DIMMs.



    I'll be interested to see what happens after booting up Windows XP again.



    Thanks again.
  • Reply 3 of 3
    hmachmac Posts: 3member
    Heh heh...after switching the RAM around, initially, everything went back to 9 gigabytes and stayed for awhile....so I thought maybe it had just needed to be reseated. Then, I booted into Windows XP for awhile. When I booted back into OSX, I found that I was back to 7 gig RAM and now the mis-read RAM was in B1 and B2. I'll give Crucial a call. Seems pretty strange to me, but I have to think there's some kind of problem with the RAM itself rather than the machine.





Sign In or Register to comment.