nMP 128GB or 64GB

Discussion in 'Mac Pro' started by Reticuli, Jan 1, 2015.

  1. Reticuli macrumors regular

    Reticuli

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    Dec 6, 2014
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    Northern Ireland
    #1
    It's pretty exciting news that the nMP now can take 32GB DIMMS. Mine will be arriving with only 12GB of ram and as I will need to remove the existing ram to add anew, I'd like some guidance on how to proceed.

    I'm going to add either 64GB or 128GB. I'll do this in stages, as I can't afford to do it all at once. So for instance add a 16GB stick each month or a 32GB stick every other month.

    I understand that the 32GB sticks have a slower speed, 800mhz or so lower I believe. Should this impact my decision? Would it significantly reduce system performance?

    It's not so much that I would need 128GB right now, but I just don't want to be adding 64 now only to throw it away to embrace 128 later, so I'd like to get it right first time.

    How do you feel about this folks? Is the speed hit a compromise too far? Or would the file caching of the extra 64GB of ram offset this?
     
  2. Meister Suspended

    Meister

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    Oct 10, 2013
    #2
    I am curious. What do you use a computer with 128gb for?
    Except for awesome multitasking every app available :)
     
  3. Reticuli thread starter macrumors regular

    Reticuli

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    #3
    Running the matrix in ram?
    To be honest I don't expect my video editing to consume anything close to that. Nor will my VMs. The limited ram slots on the nMP mean that if I get 64 and later decide I want 1278, I need to get rid of the 16GB sticks. It's a bit of a waste. I'd rather decide what I'm doing in advance and stick with it (no pun intended)
     
  4. Meister Suspended

    Meister

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    Oct 10, 2013
    #4
    If that's how you want to spend your money, go for it!
    I don't own a nMP but I reckon you could stick in 2x32gb and buy more later.
    Since the RAM in the MP is upgradeable you could always get more later.
     
  5. bxs, Jan 1, 2015
    Last edited: Jan 1, 2015

    bxs macrumors 6502

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    Oct 20, 2007
    #5
    If you frequently perform a great deal of 'buffered' data shuffling using fairly large files either reading/writing serially or randomly and this data can be kept in RAM/memory the larger the physical RAM in the Mac the better off you will be. This is because access to RAM/memory by the Applications is about 8 times faster than hauling the data off an internal SSD and some 20 times faster than hauling the data off a spinning disk.

    Having said that, it's important that all of the RAM/memory modules MUST be a matched set. This typically can only be achieved when you buy 64GB (4x 16GB modules) or 128GB (4x 32GB modules) at the same time from say OWC http://eshop.macsales.com/shop/memory/Mac-Pro-Memory#1866-memory.

    If RAM modules are not purchased in this manner and you buy the modules piece meal (say one at a time or two at a time, etc) you're likely to encounter serious issues with the hardware and/or software not recognizing or having errors using all of the RAM/memory.

    If it were me, I'd buy the 64GB (4x 16GB modules) from OWC and trade in the 3x 4GB RAM modules to OWC for $75. Then later when you have the money, buy the 128GB (4x 32GB modules) from OWC and sell the 4x 16GB modules on Craigslist or eBay or to a needy friend.

    Note: The OWC 128GB memory is a bit slower than the 64GB... but in most cases if you really need that 128GB I would not be too concerned about that.
     
  6. DeltaMac, Jan 1, 2015
    Last edited: Jan 1, 2015

    DeltaMac macrumors 604

    DeltaMac

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    Delaware
    #6
    You don't have to replace all 4 at once. If you, for example, have 64GB (16GB x 4), then you COULD upgrade with only one stick, to give 1 x 32GB, and 3 x 16GB, for a total of 80GB installed.
    You can't leave smaller sticks installed (4, or 8GB) if you add large sticks (16 or 32)

    http://support.apple.com/en-us/HT202885

    OWC is pretty good about noting when matched pairs are necessary. It's worth noting that OWC lists single chips as a possible upgrade (and sells singles or sets). I think that matched sets are nice to have, but as long as you don't mix UDIMMs and RDIMMs, you should be fine.
     
  7. ixxx69 macrumors 6502a

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    #7
    If you don't need it now (or maybe ever), does this make economic sense?

    This would currently make a little more sense if the cost difference between 64 and 128 was under 100%. But it's well over 100% (something like US$800 vs $2,000).

    It makes way more sense IMO to get the 64 now and buy the 128 when you actually need it (and then sell the 64).

    Also, yes, the 128 is currently much slower (1333MHz) than what is spec (1866MHz). While this wouldn't be noticeable just turning the computer on, for things like video editing where massive files are being loaded into RAM, it might be.

    I also agree with others that buying 1 stick at a time is asking for trouble. What happens when (if) they start releasing 1866MHz 32GB sticks and you've already bought a couple of 1333MHz sticks?
     
  8. reco2011 macrumors 6502a

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    May 25, 2014
    #8
    As a general rule of thumb if you need the memory it's better to have more, slower memory than less, faster memory. For all but the most demanding tasks memory speed is not something to worry about (aside from ensuring you get the correct speed for your system).

    I'm with the others who state that buying a 32GB stick at a premium (over two 16GB sticks) doesn't make a lot of sense if you have no immediate, or foreseeable, need for the memory. Better to buy smaller and resell later if need be.

    ----------

    Typically everything clocks down to the slowest speed module on any given controller. It's not uncommon for users to mix and match memory speeds as long as the memory meets the minimum required by the system.
     
  9. ixxx69 macrumors 6502a

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    #9
    My point was that he'd be stuck with at the slower RAM speed. Presumably he wouldn't do any mixing - he'd just get another stick of the 1333MHz (which would presumably be cheaper than the 1866MHz).

    You're correct, "typically" it should work to mix RAM speeds, but that doesn't mean it's a good idea. To guarantee the best stability, it's advised to keep the RAM specs all the same. That's not just some "according to the manufacturers" advice, that's "real world" good advice in my experience. :)
     
  10. Reticuli thread starter macrumors regular

    Reticuli

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    Dec 6, 2014
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    Northern Ireland
    #10
    64GB (4x16) it is! With a possible upgrade to 128 at a later date.
    This is why I come here, the advice is always solid.
    Thanks again lads
     
  11. nox-uk macrumors regular

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    Apr 11, 2012
    #11
    And at a later date, faster large capacity modules may be available, so you won't lose speed there.

    Nox
     
  12. Synchro3 macrumors 65816

    Synchro3

    Joined:
    Jan 12, 2014
    #12
    I doubt. Higher RAM-Speeds are nothing but smoke and mirrors, just a marketing ploy. Even 1066 MHz DDR3 is not bad compared to current RAM:

    http://www.tomshardware.co.uk/forum/314892-30-cl11-what-difference

    http://www.computerbase.de/2012-05/test-welchen-ram-fuer-intel-ivy-bridge/3/

    There is a less than 2% difference from DDR3 2133 MHz to DDR3-1333 MHz, and a 4.5% difference from DDR3 2133 MHz to DDR3-1066 MHz.
     
  13. ixxx69 macrumors 6502a

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    #13
    I agree entirely with your general point about memory speeds, but it seems like you're being senselessly pedantic to point out "much slower". I was just confirming what the OP suggested about 32GB sticks having a slower speed. They do - that's just a fact - 1333MHz is slower, i.e. has a lower data rate, than 1866MHz (if you want to disagree whether 30% lower data rate is just "slower" or "much slower", that's on you). I think I indicated pretty clearly in my post that it wouldn't have a major impact on general system performance. :rolleyes:

    That being said, you can call it "smoke and mirrors" all you want, but RAM speed is just one component in overall system performance - it doesn't exist in a vacuum. There's a tendency in various forum discussions to dismiss a few percentage points for RAM speed, a few percentage points for a faster CPU, a few percentage points for a faster GPU, a few percentage points for getting by with a minimum amount of RAM... but eventually that all adds up to a perceived difference in overall system performance.
     
  14. mindbend macrumors newbie

    Joined:
    Jan 2, 2015
    #15
    Memory Speed

    It DOES make a difference. I have a 10-core nMP (yes, I upgraded it myself). Just got a Transcend 128GB kit and benched it with the Apple 1866MHz stock units first.

    Geekbench Scores with 16GB 1866Mhz DDR3
    Overall: 3373 Single Core, 30242 MultiCore
    Memory: 3057 Single Core, 5146 MultiCore​

    Geekbench Scores with 128GB 1600Mhz DDR3
    Overall: 3354 Single Core, 30121 MultiCore
    Memory: 2864 Single Core, 4608 MultiCore​

    Interestingly GeekBench reports the memory speed as 1066Mhz, so not sure if somethings wrong or GBench is just confused. I've put a message in with Transcend to see what's up and will report back here.

    In real-world applications, I doubt the speed hit is significant enough to negate the benefits of having lots of RAM.

    I chose this due to working extensively with 4,5,and 6K video content and wanted to be sure each core had plenty of memory w/o need to cache frames. I hope it's not overkill due to the $$$'s required!
     
  15. ixxx69 macrumors 6502a

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    #16
    Maybe I'm missing something, but I'm not sure what you've proven other than it doesn't make a difference? Overall scores are identical. The memory score is just that... a synthetic benchmark that isolates memory performance but has little real-world correlation, hence the identical overall scores.
     
  16. mindbend macrumors newbie

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    Jan 2, 2015
    #17
    Don't crucify the messenger--just posting the data. Draw whatever conclusion you'd like, but the numbers are clearly different, albeit quite small.

     
  17. ixxx69 macrumors 6502a

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    #18
    Crucify the messenger? You suggested that the benchmarks you posted show that it makes a difference, and the benchmarks don't. I don't see how that's open to interpretation. That's what I found confusing. But no worries - as you suggest, you can draw whatever conclusion you like.
     
  18. mindbend macrumors newbie

    Joined:
    Jan 2, 2015
    #19
    Memory Speed

    The numbers are different, yet minutely small. It's awesome to have a pile of ram for multi-core operations, so each one can allocate significant amounts needed. I was opting for 6 GB per core, but with system overhead and consumption by another concurrent app or two, felt like 64GB was too close.
     

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