Is buffered RAM better than unbuffered?

Discussion in 'Mac Pro' started by Luba, Oct 27, 2012.

  1. Luba macrumors 65816

    Luba

    Joined:
    Apr 22, 2009
    #1
    I have a 2.66 Ghz Quad-Core 2009 Mac Pro (4,1) which takes ECC (error correction) unbuffered DDR3 PC3-8500 (1066 Mhz) with thermal sensor.

    I read that while registered/buffered RAM is one cycle slower it more than makes up for that by being faster when working with other RAM sticks. I planning on getting 8GB x 3 = 24GB to keep it at triple channel.

    I read that registered/buffered will work. If cost is not a factor, should I hunt for and get registered/unbuffered? How much should registered/unbuffered cost over unbuffered, 25% more?

    By the way, CL = 7 thus CL = 7 = 1066 Mhz?

    I also read that I can buy 1333 Mhz RAM and my Mac Pro would just down-grade the speed to 1066 Mhz. Is there any down-side to getting 1333 Mhz RAM?

    My 2009 Mac Pro has a 12 rank maximum, correct? What's better RAM, Quad-Rank, Dual-Rank, or Single-Rank? Since I have a single processor Quad-Rank is bad if I use 4 sticks since 4xQuad=16, which would go over my 12 rank maximum?

    Thanks for any help!
     
  2. Umbongo macrumors 601

    Umbongo

    Joined:
    Sep 14, 2006
    Location:
    England
    #2
    You're over complicating it all.

    I would recommend you buy three DDR3 1333MHz ECC unbuffered dual-rank modules.

    $146 with coupon code: http://www.superbiiz.com/detail.php?name=W1333EB8GM

    You don't need ECC though, so you can get consumer kits for $100 on newegg/amazon if you want.

    Each Intel memory controller can address 8 ranks of memory. Your CPU has three working together so they can address up to 8 on each channel. They can't address more than 4 at the speed you would expect your memory to run at. So you shouldn't use quad-ranked DIMMs if you think you will add a fourth at some stage - your speed would drop to 800MHz.
     
  3. brand macrumors 601

    brand

    Joined:
    Oct 3, 2006
    Location:
    127.0.0.1
    #3
    He hasn't mentioned what he will be doing so why would you just assume that?
     
  4. Umbongo macrumors 601

    Umbongo

    Joined:
    Sep 14, 2006
    Location:
    England
    #4
    I mean "You don't need to use ECC if you don't want to."
     
  5. Luba thread starter macrumors 65816

    Luba

    Joined:
    Apr 22, 2009
    #5
    I am looking for the highest quality RAM. I rather pay now than deal with problems later, besides it would cost me more in lost work. That's why for sure, I will get ECC. And I would get registered/buffered RAM if it offered an advantage. If it does offer an advantage, how much is the extra cost? Small advantage, but very high extra cost then I would skip it. :)
     
  6. Umbongo macrumors 601

    Umbongo

    Joined:
    Sep 14, 2006
    Location:
    England
    #6
    There is no noticeable performance, stability or quality difference between registered and unbuffered on a Mac Pro, buy unbuffered ECC.

    There isn't really such a thing as the highest quality memory, its a cheap mass produced product. All you can really do is buy from a company with a good warranty like OWC http://eshop.macsales.com/item/Other World Computing/1333D3W8M24K/
     
  7. deconstruct60 macrumors 604

    Joined:
    Mar 10, 2009
    #7
    If you are looking to minimize later headaches your best bet is to buy what the system vendor ( in this case Apple) says to buy. That is what they designed and tested for.

    http://www.apple.com/support/macpro/

    Unfortunately, Apple is continued down the track of watering down their "tech specs". However, either a manual ( "... Unbuffered dual inline memory modules (UDIMMs) ... " ) or knowledgeable Mac memory vendor can point to the right set.


    P.S. Apple does "lie" about max capacity though when it is relatively very expensive DIMM modules in question. But not the basic type.
     
  8. Luba thread starter macrumors 65816

    Luba

    Joined:
    Apr 22, 2009
    #8
    Thanks for your help!



    ----------

    Thanks everybody for providing their feedback. After I get some work done, I will order 24GB of RAM, hopefully there will still be power (electricity) available. Hurricane Sandy is on its way.
     

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