Installing New RAM-Proper Order For DIMMS

Discussion in 'Mac Basics and Help' started by macro, Dec 23, 2007.

  1. macro macrumors member

    Joined:
    Dec 15, 2007
    #1
    I have just ordered 2 x 4= 8Gig of RAM for my mac pro. I checked the video at OWC and it looked straight forward but have gotten conflicting info at other places. So, I am confused as to where to place new 2 G x 4 dimms and what to do with the 2-512 MB dimms that are factory installed.

    I have been told to place them as close to the logic board as I can but this doesn't help as I am not sure where the logic board is. the nomenclature of A1, A2 - B1, B2 etc doesn't tell me where the starting point of A1 is so that I can keep going with the install. I know that A is the top riser and B is the bottom. The good news is that I have a few days to figure all this out.

    I know this is going to be a snap once I get myself oriented. I just don't want to screw this up and am pretty confused.
     
  2. netnothing macrumors 68040

    netnothing

    Joined:
    Mar 13, 2007
    Location:
    NH
    #2
    Here's the chart showing the best configs. The logic board is what the risers are plugged into. So, you want to start with the slots populated closest to where you plug the risers back into.

    -Kevin
     

    Attached Files:

  3. macro thread starter macrumors member

    Joined:
    Dec 15, 2007
    #3
    I can't read the numbers on the thumbnail, even enlarged, so let me tell you what I think I know and you can correct me if I am in error.
    I get different answers as to how the slots are numbered front to back or back to front. For our purpose, let's say that slot 1 is closest to the logic board and slot 4 is closest to the side panel (removable).

    I would remove the factory RAM (2 512 MB) and set them aside. I would install 0ne each of the 2GB chips in slots one and two on riser card A. Same slots on riser card B (1 and 2). I would then reinstall the 2 512 MB chips behind the 2- 2GB chips that are now in 1 and 2 (A) in slots 3 and 4-riser card A.

    Sound correct. I have seen the Mac Pro manual say to install the 512's in 3 and 4 on card B. However, I need to deal with what I have and there are a lot of confusing answers to this question.
     
  4. netnothing macrumors 68040

    netnothing

    Joined:
    Mar 13, 2007
    Location:
    NH
    #4
    Your browser might be scaling the JPEG...after opening it...click it again to enlarge it. Or save it to your system and open it in Preview to zoom in.

    Anyway....since you are getting 8GB (4x2GB)....you'll have 2 choices...either 8GB or 9GB in the system.

    If you choose to run with just the 8GB, your config will be:

    Riser A:
    Slot 1: 2GB
    Slot 2: 2GB
    Slot 3: empty
    Slot 4: empty


    Riser B:
    Slot 1: 2GB
    Slot 2: 2GB
    Slot 3: empty
    Slot 4: empty


    If you choose to run with 9GB, your config will be:

    Riser A:
    Slot 1: 2GB
    Slot 2: 2GB
    Slot 3: 512 MB
    Slot 4: 512 MB


    Riser B:
    Slot 1: 2GB
    Slot 2: 2GB
    Slot 3: empty
    Slot 4: empty

    -Kevin
     
  5. macro thread starter macrumors member

    Joined:
    Dec 15, 2007
    #5
    Thanks Kevin. I believe you took my example and slot 1 is the slot closest to the logic board. Slot 4 is closest to the finger holes or removable panel on the side of the Mac. If so then my research finally got worked out correctly. Unless there is a reason not to I will install the two 512's in A, 3 and 4 for a total of 9 GB's.

    Part of my confusion was that I thought I had to have all the sticks exactly the same as they have to be for my PC. That would negate my using the 512's with the 2 GB sticks. Not so for Mac if I understand correctly. I guess I'm a perfectionist but I want to understand this down to the subatomic level and get it right the first time.
     
  6. netnothing macrumors 68040

    netnothing

    Joined:
    Mar 13, 2007
    Location:
    NH
    #6
    No, you just have to match Pairs of DIMMS...not all of them.

    Then only other thing you might want to research...which I don't know too much about....is DUAL CHANNEL vs QUAD CHANNEL in the Mac Pro. This is basically when you populate both risers with matched pairs....so in your case using 8GB would get you Quad Channel access....while adding the 512's for 9GB would drop you down to Dual Channel....I think. Again, I don't even fully understand it. Here are a few articles that talk about it:

    http://www.barefeats.com/quad09.html
    http://www.anandtech.com/mac/showdoc.aspx?i=2816&p=12

    You can also search this forum, or post in the Mac Pro forum asking the question....I know it's been talked about before.

    In your case where you would only gain 1GB difference between the two options.....you may want to leave the stock 512's out for better overall performance (unless you think you'll need to use that extra 1GB).

    Also....keep the stock 512's safe. If you ever need to deal with Apple support, you'll need to put them back in by themselves, without the 3rd party RAM in.

    -Kevin
     
  7. macro thread starter macrumors member

    Joined:
    Dec 15, 2007
    #7
    The second article was quite revealing as it suggests that one should go with two matched pairs per card to achieve quad. Potentially, for some applications, this will give superior speed to a dual set up. That's the gist and that is what I will do. I will place the 2 512's in a safe place in case I should have a failure with the other memory. Interesting stuff. I think a bit above my head in tech. language but, never the less enlightening. Thanks a lot for pointing these out.
    I have about a week to prepare for this and the more info the better. I now have a limited but clear understanding of how all this works which I like a lot better than just going through the motions of plugging or unplugging. A Chimp can do that.
     
  8. macro thread starter macrumors member

    Joined:
    Dec 15, 2007
    #8
    Thank You

    I just put the Xtra 8 gigs in my Mac Pro. I am very thankful for the consistency of help that got me on task in a correct manner. It's done and I thank each of you who contributed to allay the natural fear that anyone would have when gutting a $3000.00 fish. It went beautifully. I am up and running and my photo software is as fast as 1/1000th at f 1.2. I am very grateful for the help.
     
  9. netnothing macrumors 68040

    netnothing

    Joined:
    Mar 13, 2007
    Location:
    NH
    #9
    Glad everything worked out. I too just put another 8 GB in my Mac Pro.

    -Kevin
     

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