1600Mhz DDR3 Ram in a Mac Pro 5,1?

Discussion in 'Mac Pro' started by tripmusic, Nov 13, 2015.

  1. tripmusic macrumors 6502

    tripmusic

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    #1
    Can you use 1600Mhz DDR3 RAM in a Mac Pro 5,1 (Flashed from 4,1)? I saw a user on Geekbench using it and had considerably higher benchmarks than users with 1333Mhz RAM. Can it actually work and make a difference, pros/cons?
    http://browser.primatelabs.com/geekbench3/2798779
     
  2. h9826790 macrumors 604

    h9826790

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    #2
    You can use 1600MHz RAM, but will only run at 1333MHz. You can't take any benifit from it in a real Mac Pro.
     
  3. tripmusic thread starter macrumors 6502

    tripmusic

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    #3
    Hmm... so it was just coincidental that they had higher benchmarks than users with 1333?
     
  4. h9826790 macrumors 604

    h9826790

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    #4
    I didn't look at the details. But, if that record is real, may be that's from a hackintosh which can OC the RAM.
     
  5. SoyCapitanSoyCapitan macrumors 68040

    SoyCapitanSoyCapitan

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    #5
    Tylersburg (Intel 5520/5500/X58) has a 1333Mhz front side bus. Geekbench's site is full of weird records, some are manually faked and some are because of fake SMC in Hackintosh making it look like a real Mac model.
     
  6. tripmusic thread starter macrumors 6502

    tripmusic

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    #6
    Ok, thanks guys for clearing that up. 1333Mhz it is then for my soon to be 2009 MP to 5,1 with a W3690. Will be my fastest Mac yet, can't wait!
     
  7. benjaprud, Nov 15, 2015
    Last edited: Nov 15, 2015

    benjaprud macrumors member

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    #7
    If you aim for absolute best performance, use 3 identical dual-ranked unbuffered 1,5V RAM modules and leave the slot the closest from the CPU empty. Dual-ranked ECC modules should have 9 chips on each side (non-ECC have 8 on each side).

    High capacity quad-ranked modules will run at 1066MHz and 4 quad-ranked modules will run at 800MHz. However if you need lots of RAM then high capacity quad-ranked modules is the only way to go, you'll still benefit from it if you actually use the extra capacity.
     
  8. tripmusic thread starter macrumors 6502

    tripmusic

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    #8
    Ok, but I want 1333Mhz for a 5,1, ya? Just did a quick search on this dual/quad ranking. So avoid the quad because it down clocks the speed? I already ordered 4X4GB@1333 for like $35. I can always cancel or return the order. Maybe I'll look for 3 dual ranked 8GB sticks. Thanks for that info!
     
  9. benjaprud, Nov 15, 2015
    Last edited: Nov 15, 2015

    benjaprud macrumors member

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    #9
  10. tripmusic, Nov 15, 2015
    Last edited: Nov 15, 2015

    tripmusic thread starter macrumors 6502

    tripmusic

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    #10
    Thanks. That's some good info. Need to absorb all of that. Question... above you state that 2R should have 9 chips, but in your posting in the link you said 1R should have 9 chips? And those are ECC registered, but your saying for optimal performance I should look for non-ECC sticks? I thought the MP's used ECC?
     
  11. benjaprud, Nov 15, 2015
    Last edited: Nov 15, 2015

    benjaprud macrumors member

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    #11
    I didn't recommend using non-ECC (registered ≠ ECC, registered is opposed to unbuffered), ECC doesn't affect performance (well at least I haven't read about it having an influence on performance), you can use both but ECC is more reliable.
    9 chips on both sides.
     
  12. tripmusic, Nov 15, 2015
    Last edited: Nov 15, 2015

    tripmusic thread starter macrumors 6502

    tripmusic

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    #12
    Ok, sorry about that. As you can tell I'm clueless about this memory stuff, but starting to get it now. Seems like most of the stuff on eBay is registered. Actually, the 16GB I got was too, so I should definitely cancel that. Any suggestions where to get the type of sticks you stated without breaking the bank? Also, are the heat sinks needed or not necessarily?
     
  13. h9826790 macrumors 604

    h9826790

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    #13
    Technically, ECC is a tiny bit slower, but should be almost zero real world difference. So, ECC is a better choice.

    Use only 3 sticks to optimise the triple channel architecture is more or less the same thing. Even though benchmark will show the difference. For most real world applications, there is virtually zero performance plenalty. So, install more usually better than intentionally install less RAM but optimised for triple channel.
     
  14. benjaprud macrumors member

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    #14
    As h9826790 said, these make negligible real world performance differences, but might show on Geekbench if it is the figure you're concerned about.

    To clear things up, first rule of thumb is if you need more RAM then put more, second is don't mix different memory types, third is put 3 sticks, the rest makes almost no difference.
     
  15. Arron Rouse macrumors regular

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    #15
    You could try searching for this part number: KTA-MP1333/8G or KTA-MP1333/4G

    Those are the exact types of stick for the Mac Pro but can be expensive. They are specific for the MP in that not only are they ECC but they also have a thermal sensor. However, it's not too much more than non-ECC without the thermal sensor (which you can use if you want). In my mind, it's worth spending the extra.

    Quantity wise, it depends on your use. There are four memory slots in the 5,1 and you should always populate the first three. The processor interleaves the first three making them act like one big, very fast memory stick. The fourth runs by itself at standard speed.

    So, if you use one or two programs that use a lot of memory -- video editor, music composition, rendering, etc. -- it's worth putting the fourth RAM stick in place because more memory is better than using the swap file (which is what happens if your programs need more memory than you have RAM).

    However, if you use lots of programs at the same time that are performance sensitive -- e.g. several virtual machines -- it's worth sticking with just the three memory sticks or you can get odd performance issues.

    If you're just a normal person using the MP as a desktop, it doesn't really matter whether you put three or four in there.
     
  16. flowrider macrumors 601

    flowrider

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    #16
    Heatsinks are not needed on a 4,1 to 5,1 cMP. My memory supplier since 1986 has been:

    http://www.datamemorysystems.com/ap...06ghz-md771ll/a-cto-mid-2012-memory-upgrades/

    They are Mac specialists. Other members of this forum have used them, and all have been highly satisfied. I highly recommend them.

    Lou
     
  17. tripmusic thread starter macrumors 6502

    tripmusic

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    #17
    So, even if you use 4 sticks @1333Mhz the first three slots will utilize that speed and the fourth slot will run @1066, or all four sticks will run at the slower 1066Mhz?
     
  18. tripmusic, Nov 16, 2015
    Last edited: Nov 16, 2015

    tripmusic thread starter macrumors 6502

    tripmusic

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    #18
    Ok Thanks. I'm also considering OWC, the prices seem comparable.

    Edit: Giving DMS a try. 24GB for $177. Can't wait to get all my components in the mail and start putting this beast together
     
  19. tripmusic thread starter macrumors 6502

    tripmusic

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    #19
    Will be used with DAW recording, Pro Tools 11. I think 3X8GB will serve me just fine
     
  20. Arron Rouse macrumors regular

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    #20
    No, all of them will run at 1333MHz -- not sure what Benjaprud was thinking of but, as far as I know, his comment was not true for the 4,1/5,1.

    The first three memory sticks are interleaved. It's kind of like instead of three 1333MHz sticks, they act like a single 3999MHz stick. Whereas the fourth stick always just runs by itself.

    The upshot is that any data that gets written to the fourth stick (at the top of memory so the last to be filled) is much slower to access.
     
  21. benjaprud, Nov 19, 2015
    Last edited: Nov 19, 2015

    benjaprud macrumors member

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    #21
    I'm not sure which comment you are referring to. If you put 4 DIMMs they will all run at 1333MHz (except 4x quad-ranked will run at 800 and 4x 1,35V will run at 1066), but in 2-way-interleaving mode instead of 3-way. You can read my link on msg #9 which has all the information and links to datasheets from Intel, IBM and others, here's an excerpt :

     
  22. Arron Rouse macrumors regular

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    #22
    Sorry, misread your earlier post. I'd read it as putting four sticks in will drop the clock on the RAM. From his response, I think tripmusic did the same.

    Had a quick squirt through those links and I want to put in a word of caution. As far as I know, the Mac Pro does *not* use the same configuration as that IBM kit. The interleaving is controlled by a setting in the BIOS/EFI and it is my understanding that the Mac Pro does not switch to dual-channel mode.

    There are lots of sites that assume dual channel (2 + 2) because of the performance hit and the fact that lots of PC kit uses dual channel if there are four slots occupied. But ages ago I dug into it and found some obscure information that said the Mac Pro went with 3 + 1 instead.

    However, it took hours to find at the time and I really don't have the hours to hunt it down again so feel free to treat my word of caution as "some bloke on an Internet forum said" if you want :)

    Suffice to say that we probably both agree that 3 sticks are faster than 4 unless you start to hit the page/swap file.
     
  23. benjaprud, Nov 20, 2015
    Last edited: Nov 20, 2015

    benjaprud macrumors member

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    #23
    Yeah, we can agree it's very simple and very complicated at the same time for a performance difference that's hardly noticeable.
    That's about it.
    Might be. The way I understand it from what i've read is that most if not all consumer PCs of the cMP era had processors with only 2 memory channels (and motherboards with 4 colored memory slots that would indicate so). People also tend to confuse between dual-channel and 2-way-interleaving which is not exactly the same thing. While working in 2-way-interleaving mode, the Nehalem/Westmere Xeons still make use of their 3 memory channels, it just adresses them differently. As for the influence of the EFI settings, we might never know.

    Whatever the details most articles on the subject seem to agree that the performance penalty from using 4 sticks is negligible (1 to 5% on most usages on the fastest Westmere CPUs), but still greater than the penalty from using 1066 instead of 1333 (thus going from a balanced 1066 setup to an unbalanced 1333 is pointless performance-wise). This paper is quite a well explained summary of what I've found so far.

    However when I see people trying to squeeze the best out of the beast (and break GeekBench records) by putting W3690 or equivalent CPUs in their MPs I think this kind of information might be of interest to them, but it's always difficult to tackle the subject without confusing people.

    It's hard to rely on GeekBench results (and they don't reflect real world performance) but to illustrate I've tried to find some relevant ones with the same configuration and that seem to be from real MPs, one with 24GB (3x8) and one with 32GB (4x8). You can tell the difference under "Memory Performance". With a balanced 1066 setup, I get scores closer to the first one than the second one.
     

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