Mac Pro RAM - does location really matter?

Discussion in 'Mac Pro' started by orangezorki, Oct 20, 2006.

  1. orangezorki macrumors 6502a

    Aug 30, 2006
    I finally collected my Mac Pro at the Apple store this evening. So far, everything is beautiful - it's just so much more solid than anything else I've used. And it really is very quiet - no more annoying than the 24" iMac I sent back for sound issues, and this one I get to put under the desk. Considering the extra power, it's far superior.

    Only one problem, and it's not that bad - the 'genius' put the extra gig of memory on the top riser, along with the default sticks. I know it's not the best place for them, but in real terms, am I going to see any difference? I'm not a HD video pro or anything, and in all reality at the moment some gaming will be the most I'll throw at it. Would you bother swapping the FB-DIMMs? I'm sure I can do it, but it boots fine, tests fine, and they cost sooo much...

  2. CHROMEDOME macrumors regular

    Apr 8, 2005
    Bay Area/LA
  3. Chundles macrumors G4


    Jul 4, 2005
    The RAM should be installed following the instructions printed inside the case. If they're not then take them out and put them in properly.
  4. petite macrumors member

    Aug 26, 2006
    To put it plain and simple....

    Yes. It does matter.
  5. robbieduncan Moderator emeritus


    Jul 24, 2002
    By having them in the wrong slots you have half the memory bandwidth you'd have if the RAM was in the correct slots. That's worth fixing.
  6. orangezorki thread starter macrumors 6502a

    Aug 30, 2006
    Suppose so, at least it will make me check the bottom riser is working.

    If a 'genius' can't follow a diagram on the inside of the door, what sort of super humans does that make us? Having said that, one of the sales assistants hadn't heard of ATI. I had to spell it out...

  7. PowerMike G5 macrumors 6502

    Oct 22, 2005
    New York, NY
    I'd install it on the lower risers so you can take advantage of the quad channel architechture ...
  8. techster85 macrumors regular

    Oct 17, 2006
    Lubbock, TX
    I think it does make a speed difference, even if you aren't really doing anything heavy duty (HD video, etc.) Plus, I'd say if Apple suggests that you do it that way, then you do it that way haha.

    Also, I installed 2x1gb into my MP along with the stock 2x512mb. I moved the 1 gb riser to the bottom and the 2 gb to the top, thinking it might make a difference in speed. But does it really? or did I just take an extra step?
  9. tehsuck macrumors newbie

    Oct 23, 2006
  10. orangezorki thread starter macrumors 6502a

    Aug 30, 2006
    Thanks again everyone - I switched them the next morning, and the amazing results are...

    Well, I haven't noticed any, but it's good to know everything is now as it should be. Overall enjoying the Mac Pro experience. Everything is working well, and the worst annoyance (now I've put a silencer on the x1900xt) is a intermittent clicking noise - sounds like a fan ramping up and down, but I don't always hear it, and it might well be the HD (but in a non-OMG, I'm going to lose my data! kind of way.) If that's the wost thing, then things aren't too bad.

    Oh yeah, it's definitely teh snappy.

  11. BackInTheSaddle macrumors regular


    Aug 20, 2002
    Olympic Peninsula, WA
  12. crazycat macrumors 65816


    Dec 5, 2005
    I downloaded the .pdf and i cant understand it, i am no computer expert. What dose it mean by DIMM's? If i get 6GB worth of RAM which slots do i put them in?
  13. CanadaRAM macrumors G5


    Oct 11, 2004
    On the Left Coast - Victoria BC Canada
    A DIMM is a Dual Inline Memory Module -- that is, one memory 'stick' that you are installing. The MacPro uses FB-DIMMs, (Fully-Buffered DIMMs) which are a specific type of module.

    The MacPro has 8 memory sockets, each can take one DIMM. The sockets are divided into two "Riser" cards, 4 sockets each. Each riser has sockets numbered 1 through 4. You must install RAM in pairs of identical DIMMs.

    To install RAM, follow this order:
    1st pair -- Top Riser: Sockets 1 and 2
    2nd pair -- Bottom Riser: Sockets 1 and 2
    3rd pair -- Top Riser: Sockets 3 and 4
    4th pair -- Bottom Riser: Sockets 3 and 4

  14. StealthRider macrumors 65816


    Jan 23, 2002
    Yokosuka, Japan
    It matters - and Apple has instructions printed on the inside of the case, and probably in your manual as well. You need full memory bandwidth when dealing with crappy FB-DIMMS...
  15. crazycat macrumors 65816


    Dec 5, 2005
    /bow thanks for the information its a lot of help to me.
  16. Sun Baked macrumors G5

    Sun Baked

    May 19, 2002
    Only one pair of DIMMs on each riser is active at a time, the same pair of DIMMs on each riser.

    Which is why you follow CanadaRAM's method for putting memory into the Risers.

  17. freezerburrn macrumors member

    Aug 20, 2006
    La Habra, CA
    What exactly is a silencer David? I'm really interested in one because the X1900 is pretty loud.
  18. orangezorki thread starter macrumors 6502a

    Aug 30, 2006
    It's basically a replacement heatsink and fan - not too difficult to install, but obviously if you kill the card while doing it you're SOL. The one that most of us on these forums have is from Artic Cooling, called the Accelero X2.


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