How to tell Memory Riser A & B apart (2008 MP)

Discussion in 'Mac Pro' started by fridgeymonster3, Aug 22, 2012.

  1. fridgeymonster3 macrumors 6502


    Jan 28, 2008
    I took my early 2008 Mac Pro apart this afternoon to do my annual cleaning and to do some upgrades (see pic). I removed both memory risers without remembering which riser was A and which was B. In the past, if I put the riser back in the opposite way, my Mac Pro refuses to start. I'd rather not have to futz around with the memory risers, can someone tell me how to distinguish the risers from each other?

    Attached Files:

  2. PowerPCMacMan macrumors 6502a


    Jul 17, 2012
    PowerPC land
    Hi, having owned an 08 Mac Pro myself the boards are identical. It does not matter which one is A or B, as both are the same. I suppose you could take a sharpie and write an A for one, B for the other. Just be sure you don't write on a contact.

    Best to write it off to the side, near the copyright dates.
  3. paulrbeers macrumors 68040

    Dec 17, 2009
    My 2006 doesn't care. I assume if it mattered Apple would have differentiated the boards... They are smart like that.
  4. snberk103 macrumors 603

    Oct 22, 2007
    An Island in the Salish Sea
    I have the 2008 8 core, and recently needed to swap the A & B risers to diagnose a memory problem. My system didn't care which riser went where.

    If your's is being finicky then you may have a bad one. At one point I thought I needed a new one, and found out that they were surprisingly cheap. The store (Apple authorized, not an Apple store) quoted me $100 Canadian for a replacement. Luckily I didn't need it. And by "cheap" I mean by Apple's standards... :)
  5. thehimay, Aug 22, 2012
    Last edited: Aug 22, 2012

    thehimay macrumors member

    Mar 17, 2009
    Toronto, ON, CA
    The risers are dictated/named by the ports on the logic board itself. In the current layout you have shown:
    'Riser A' is the upper (towards the PCIe slots) riser card slot.
    'Riser B' is the lower (towards the case bottom) riser card slot.
  6. Snowshiro macrumors 6502

    Jan 12, 2008
    Excactly that. The actual boards that hold the memory are identical. If you slide the board into the top slot, it becomes Riser A. If you slot it into the bottom slot it becomes Riser B. Which way you do it doesn't matter (unless something is faulty).
  7. pprior macrumors 65816

    Aug 1, 2007
    Wow, I just spray compressed air around in there. Way too much work, imo.

    And it doesn't matter - they're the same.
  8. Phrygian macrumors regular

    Nov 26, 2011
    i have an early 2008 as well and it is very dusty.... I haven't had the guts to take off the front fan unit.

    and you got quite a lot of storage on that, kudos
  9. fridgeymonster3 thread starter macrumors 6502


    Jan 28, 2008
    Thanks for the replies. I thought the Memory boards were interchangeable, I just had a problem one time that was solved by swapping the boards. I didn't have any problem last night when I started my MP back up.

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