Crazy idea. 32gb ram modules in a cMP. Anyone tried this?

Discussion in 'Mac Pro' started by William Payne, May 22, 2017.

  1. William Payne macrumors 6502a

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    #1
    I'm not in a position to test this as I don't have the ram but I am really curious if this would work. I don't need this much ram I'm just curious.

    With the ability to upgrade 4,1 and 5,1 cMP to use x5690 cpu's the amount of ram the CPU can handle is well over 250gb according to intel arc.

    The 16gb 1333 ram sticks you can get for Mac pros are pc3-10600 ram. You can get 1333 speed pc3-10600 ram in 32gb modules.

    Why would the Mac Pro 4,1 (when flashed to 5,1) and 5,1 models not recognise the 32gb modules when they are the speed and configuration as the 16gb sticks just more memory? Would a 32gb stick draw too much power?

    Factoring in that you can get 32gb sticks at 1333 speeds for the 6,1.
     
  2. keysofanxiety macrumors 604

    keysofanxiety

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    #2
    I can't speak for the Mac Pro, but it may be a similar situation to the cMBP. Although the CPU itself in the cMBP supports up to 32GB RAM, the CPU doesn't detect more than 8GB RAM per DIMM, so fitting 2x16GB modules just won't boot.

    I'm sure I'll be shot down if I'm biblically wrong but I imagine from your description it's something similar. :)
     
  3. h9826790 macrumors 604

    h9826790

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    #3
  4. tracer1 macrumors member

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    #4
    From what I understand ( & could be totally wrong) the 4,1 flashed to 5,1 will still only show 1066 even with 1333 memory in it. You would have to change the processor (s) to 5650 and above to show 1333. Even on the 2010 5,1 the processor(s) have to be 5660 or above to show 1333. And some processors have to be 1R memory (not 2R) to do that. I have the 2010 5,1 8 core 2.4. Even though I have 32gigs of 1333, it still shows 1066. These macs shipped with the 5620 processors so in order to show 1333 I would have to change the processors to 5650 or above to actually show 1333. I even heard some nahelem (overlook the spelling) processors won't run them anyway. As I said, I'm not a mp guru, just what I have heard or read, so take it with a grain of salt. I may have it wrong but some of the guys on here can maybe clarify it in a much simpler form.
     
  5. blackdbird macrumors newbie

    blackdbird

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    #5
    this might help , mine is 2010machine with W3690 single CPU with 32gb 1333 ram
     

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  6. William Payne thread starter macrumors 6502a

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    #6
    is that just one stick of ram? if so what ram is it? as what I'm talking about is whether you can put a single 32gb ram stick into the individual ram slots.
     
  7. h9826790 macrumors 604

    h9826790

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    #7
    We are talking about the 32GB stick, not 32GB RAM.

    e.g. With the W3690, 3x32GB = 96GB RAM
     
  8. tracer1 macrumors member

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    #8
    I was referring to the 4,1 flashed to 5,1 not showing the memory at 1333. It won't unless you upgraded the processors. My quad has 32 gigs but that 8 sticks @ 4 gigs each. My 2.66 (single cpu ) Only has 10 gigs. Never thought about a 32 gig module. The op didn't specify single or quad machine, just 4,1 flashed to 5,1. I think all that affects are updates & software so far. For a single cpu, that would be 128gigs on memory. Don't see why it couldn't handle it but unless you changed the processors, why bother. It would still show 1066. As he said though, if changed to the 5690 processor(s), yes it should show 1333Mhz. Personally don't have the need for that much memory but if he runs it would like to know the results.
     
  9. h9826790 macrumors 604

    h9826790

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    #9
    But why you suddenly talk about 1333 vs 1066?
     
  10. blackdbird macrumors newbie

    blackdbird

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    #10
    they are 8x4 1333mhz rams my processor is W3690 and technically it supports max 24gb and i m running 32gb .... anyways intel x5690 support upto 288gb , so technically it should work and if the motherboard is supporting x5690 then it should support 32gb sticks too and the only way to findout is to test yourself and update . . .
     
  11. AidenShaw, May 30, 2017
    Last edited: May 30, 2017

    AidenShaw macrumors P6

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    #11
    How about y'all using standard nomenclature - and discuss using 32 GiB DIMMs?

    Your word-salad of incorrectly used terms is embarrassing. There are no 16gb or 32gb DIMMs on the market, so it is nonsense to discuss whether any Apple system supports non-existent memory DIMMs.
     
  12. William Payne thread starter macrumors 6502a

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    #13
    Ok I may not be an expert at all the technical lingo but this is what I am talking about

    http://www.servermonkey.com/32gb-memory-upgrade-kit-1x32gb-pc3-10600r.html
     
  13. h9826790 macrumors 604

    h9826790

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    #14
    By considering dual X5690 can only boot with 5x 32GB DIMMs sticks. And we don't know the exact spec of that particular DIMM. A single X5690 5,1 may only able to boot with just 2 of them.

    And one of the problem is that this is a 4Rx4 DIMM, which may cause boot / speed issue (this usually only happen when all 4 slots are used).

    So, the only way to find out is actually buy 4 DIMMs from a seller that have proper return policy. And test it if this DIMM can actually work. And how many of them is the limit. If doesn't work, return them to minimise the lost.
     
  14. jubel macrumors newbie

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    #15
  15. Fooze, Aug 30, 2017
    Last edited: Aug 30, 2017

    Fooze macrumors newbie

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    #16
    I couldn't find a solid answer to William Payne's original question. I have a 2009 Dual CPU Mac Pro currently with dual X5675 processors installed. I bit the bullet and ordered a stick of Hynix 32GB 4Rx4 PC3L-10600R. It doesn't seem like any companies make 32GB sticks in the 2R configuration. I did a PRAM reset before firing up the 2009 Mac Pro every time.

    Experiment 1 - 2009 Mac Pro with dual X5675 3.06GHz Hex Core Processors, 1x32GB=32GB Installed
    The 2009 Mac booted with a single 32GB stick of RAM installed but in "About this Mac" it shows "32 GB ???". Under the Memory tab it shows 32GB are installed on the top, but goes on to show that "8 memory slots are available". In the System Report Memory tab it again shows that all 8 slots are empty.

    Experiment 2 - 2009 Mac Pro with dual X5675 3.06GHz Hex Core Processors, 1x32GB + 7x8GB = 88GB Installed
    This was the same computer as above but I populated the remaining 7 RAM slots with Hynix 8GB 2Rx4 PC3-10600R memory. About this Mac shows 88GB of ram installed but shows the slot with the 32GB stick present as "Empty". Also noted that the 1333MHz ram is running at a reduced 1066MHz.

    Experiment 3 - 2009 Mac Pro with dual X5675 3.06GHz Hex Core Processors, 1x32GB + 5x8GB = 72GB Installed
    This was the same computer as above but I removed the 8GB sticks present in Slot 4 and Slot 8 knowing that these 2009 Mac Pros are optimized when running with triple memory channels. Similar result to the above configuration. 72GB shows up, but the slot with the 32GB stick installed appears to be "Empty" under the memory tab. Even after a PRAM reset the memory is still running at the reduced 1066MHz.

    In summery, the 2009 Mac Pro will boot with a 32GB stick installed, but it doesn't seem like the Mac is recognizing it properly. All of this was tested on Yosemite. Might be worth trying on a newer version of OSX. Let me know if there's anything else worth trying with this stick. I have a single CPU 2010 that I'll test with this 32GB stick as well.
     

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  16. h9826790 macrumors 604

    h9826790

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    #17
    Thanks for the tests and detailed report. It seems that ??? is the standard behaviour for pure 32GB sticks config.
    [​IMG]
     
  17. LightBulbFun, Aug 30, 2017
    Last edited: Aug 30, 2017

    LightBulbFun macrumors 6502a

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    #18
    has anyone tried 32GB Sticks with the new 2017 boot rom?

    from what iv seen all the 32GB RDIMM I have seen have been DDR3L sticks and NOT DDR3 sticks, the 2010 firmware might not know what to name these sticks, hence the ??? for a name. DDR3L being a low voltage version of DDR3.

    also do note the only CPUs that the Mac Pro is compatible with that support DDR3L RAM sticks are the Westmere Xeons, the Nehalem Xeons do not support DDR3L AFAIK.

    edit: it would also be worth testing some smaller PC3L (DDR3L) RAM sticks and see if they do the same thing.
     
  18. flowrider macrumors 601

    flowrider

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    #19
    You really can't expect results in Yosemite to be applicable today!

    Not even the latest releases of Yosemite??????

    Lou
     
  19. h9826790 macrumors 604

    h9826790

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    #20
    DDR3L is fine, I did try both 8GB non ECC, and 16GB ECC, both correctly identified.

    AFAIK, DDR3L has backward compatibility to DDR3. Just like the cMP natively only has USB 2.0 support, but if you plug in a USB 3.0 stick, it will still work, but just at USB 2.0 speed. The same rule applicable on DDR3L, if you install DDR3L inside cMP, regardless the CPU model, they will run at DDR3 voltage (not DDR3L).
     
  20. dabotsonline, Aug 31, 2017
    Last edited: Aug 31, 2017

    dabotsonline macrumors member

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    #21
    My understanding is that Boot ROM MP51.0084.B00 is the latest for MacPro5,1 on High Sierra Developer Beta 8 / Public Beta 7.

    Is it still limited to 5 sticks x 32GB = 160GB RAM in both macOS and Boot Camp Windows 10 Pro and Enterprise 17.09 preview? Has anyone tried Windows 10 Pro for Workstations 17.09 preview?
     
  21. h9826790 macrumors 604

    h9826790

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    #22
    No idea, only one member tested this config and reported so far. That's was with Yosemite. Since then, almost no discussion on this topic.

    According to his post, he said that the cMP will have "kernel panic" if go pass 160GB (5x32GB + 16GB). Therefore, it seems not firmware limiting even in the old days. If firmware limiting, I expect the computer can't even POST.

    I am not 100% sure when and how the KP happen. He also mentioned that the 6th 32GB stick is not recognised. So, possible the cMP can work with 6x32, no KP, but the Yosemite can only recognise 160GB RAM.

    However, he also mention that once go beyond 160GB, the cMP "no longer boot". So, it's a bit confusing. I assume he means the cMP "cannot function properly (or unable boot to desktop)", but not really no POST.

    If all the above are correct, we may not need any new firmware to go beyond 160GB. In fact, I don't think Apple will care about this and improve anything on this matter. But OS upgrade surely possible to make the cMP able to go beyond 160GB RAM. But since no 32GB DDR3 dual rank DIMM available, we have no idea if that limitation is coming from the memory rank, or OS, or something else.
     
  22. kwikdeth macrumors 6502a

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    #23
    a few notes I thought I would add here which may clear up some confusion:
    1066mhz vs 1333mhz:
    two things can affect this here. One is CPU. Not every LGA1366 CPU was able to run 1333mhz memory. Even some CPUs in the same family would run it differently. This is not an Apple ROM issue. This is how the processors were designed by Intel to create segmentation in the product line. Even the base 2.26ghz 2010 Mac Pro only runs its memory at 1066, whereas the higher speed machines ran at 1333.
    You can see the different memory speeds across the lineup here:
    https://en.wikipedia.org/wiki/List_...cessors#Xeon_5000-series_.28dual-processor.29

    Second: memory ranking. this is a very complicated topic and a lot of people are not informed when it comes to this one. Memory larger than 16gb (this level has increased over time, used to be back in like 2009 stuff over 4gb) is built slightly differently than other memory, and due to the increased electrical load (due to more or higher density memory modules) in almost all cases the use of 4-rank memory will result in the memory downclocking to the next speed, or in some cases, even down to the base multiplier for the bus (in the mac pro's case, 800mhz) This is true when using all 4-rank memory or in mixed cases of 1, 2 and 4 rank memory. Again, this is not an Apple ROM limitation. This is purely the physical design of the RAM which causes this. Part of the reason 4-rank memory exists, is because it allows for denser memory chip configurations. Im almost positive you will have a hard time, if not impossible time, finding 32GB ram which is not 4-rank.


    as for the 160gb config, I am really not sure why this is other than a possible ROM block. But also, doesnt OSX have a 128GB limit? Perhaps the problem is not the hardware here but the OS? Has anyone tried booting into a Bootcamp install and seeing if the same issue is present?
     
  23. h9826790 macrumors 604

    h9826790

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    #24
    Couldn't quite remember the exact OS version, but from memory 96GB limit is pre-Mavericks. After that, 128GB is just the max demonstrated limit, AFAIK, by that time, no one every try to go above that (or at least do that in the "correct" way). So, no one knows what's the exact limit is. However, we generally treat this 128GB as a hard rule. The fact is, MacOS may never ever limit the RAM to 128GB. Just like the 48GB max for W36xx CPU, until MVC realise it can boot with 3x16+8. That 48GB was a hard limit for quite a period of time for us, but at the end, it's just the demonstrated limit, not the real hard limit, we just don't know the correct way to go around it.

    I personally didn't experience the "no boot" due to improper memory rank DIMM installed. I totally understand that high memory rank DIMM can cause RAM to run slower. I still own such 8GB UDIMM on my hand now. 3 sticks run at 1333, 4 sticks can only run at 1066. However, form memory (more than a year ago), someone here reported that his Mac can't boot when all slots used, his total memory size definitely not over the known limit. So, we believe (without another other explanation at that moment, but also no prove either) that imporper memory rank DIMM may cause no boot on cMP as well. But I must emphasis, this is just a theory for may be 1 or 2 cases so far.
     

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