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MP 7,1 Best RAM configuration for the 2019 Mac Pro
- Thread starter jasoncarle
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Ah sweet!
Do you think though that it’s gonna have a dramatically negative effect on performance compared to if I just use my 6 x 32 dimms?
Or compared to if I get another two 8gbs? (They’re so cheap, I could easily do that if it dramatically helps..)
Can you tell me what would be the right order in this scenario with 6x32 and 4x8gb?
and any ideas how I can measure the performance of 6vs10 dimms ?
/edit: was reading again in the official Apple document and thy clearly state: don’t mix ram sizes for optimal performance and it says that 10 dimms are NOT supported.
I assume the correct way is to install the 32's as if the machine had only six DIMMs, and then install the 8's to fill out as per the ten DIMM diagram. Alternately, leave the factory 8's where they are, and install the 32's as if you were upgrading from six to twelve DIMMs.
Someone needs to do benchmarks. There could be strange configurations that work, e.g. the iMacs where certain combinations of three DIMMs are optimally installed in an unexpected way.
Rules that can be seen in Apple's recommendations: First, equalize capacity across channels. Second, DIMMs go in the channels closest to the Xeon. Third, for siamese socket pairs (i.e. wired in parallel) a solitary DIMM goes furthest* from the Xeon.
* This is for signal integrity. You don't want an unterminated signal bouncing off an empty socket and returning to a used socket.
Then why do the RAM wind tunnels show a diagram of which sockets to use with 10 DIMMs?
The way I see it is...
6 DIMMs will give you 3 memory channels
12 DIMMs will give you 6 memory channels
The difference in memory access performance is......I dunno.
If you never intend to upgrade your memory configuration in the future 12 x 32GB will be slightly cheaper and slightly faster , if the Mac follows the PC side's performance with UP 12 memory slot Cascade Lake Systems .
It should , since the two memory controllers are in-silicon for both platforms . The processor directly talks to the memory modules and the platforms don't need an onboard controller chip .
6 matching DIMMs should provide 97 % max memory bandwidth .
12 matching DIMMs should provide 100 % max memory bandwidth .
If you do intend to upgrade later , go with the 6 x 64GB configuration ( uses one controller ) . You should be able to install another set of six matching memory modules ( uses the other controller ) , but they don't have to be 64GB modules . The basic characteristics of all System modules should match , though ( ECC , latency rating ( eg CL 21 ) , speed ( eg 2933 MHz ) , etc .
We're waiting for someone to perform some comprehensive memory tests with the MP7,1 .
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Hello,
I receive my Mac Pro 2019 (24 thread) and put 6x64 from OWC in it. I started the computer and made OS X update like usual. Since this moment, impossible to boot the computer. It entered in a boot loop.
So I put back the 4x8 Ram from Apple, and boot again... impossible to restart the computer. It boots, the apple logo and progress bar appears and when it reaches 3/4 it restarts.
I called Apple, they gonna change my computer, but before send it back I booted it in Detail mode (command + V). The boot sequence crashes (and reboot) after this message : In Memory panic stackshot succeeded ** bytes traced 324304 **
So, do you think it's connected with a OWC RAM problem (that corrupted the machine during the OS X update) ? Is it a T2 chip problem (Does Apple want we use their expensive RAM ?) ?
Anyway, it's not very reassuring to ave a problem like that with a 26'000 USD machine.
Best
Robin
PS : sorry for my English, French is my mother tongue
I receive my Mac Pro 2019 (24 thread) and put 6x64 from OWC in it. I started the computer and made OS X update like usual. Since this moment, impossible to boot the computer. It entered in a boot loop.
So I put back the 4x8 Ram from Apple, and boot again... impossible to restart the computer. It boots, the apple logo and progress bar appears and when it reaches 3/4 it restarts.
I called Apple, they gonna change my computer, but before send it back I booted it in Detail mode (command + V). The boot sequence crashes (and reboot) after this message : In Memory panic stackshot succeeded ** bytes traced 324304 **
So, do you think it's connected with a OWC RAM problem (that corrupted the machine during the OS X update) ? Is it a T2 chip problem (Does Apple want we use their expensive RAM ?) ?
Anyway, it's not very reassuring to ave a problem like that with a 26'000 USD machine.
Best
Robin
PS : sorry for my English, French is my mother tongue
6 DIMMs gives you 6 channels in use.
12 DIMMs gives you 6 channels in use with half the DIMMs not enabled during memory commands.
Table from "About this Mac":
Slot Channel DIMM
1 F 1
2 F 2
3 E 1
4 E 2
5 D 1
6 D 2
-Xeon-
7 A 2
8 A 1
9 B 2
10 B 1
11 C 2
12 C 1
With six DIMMs, Apple suggests using slots 1, 3, 5, 8, 10, and 12. They correspond to channels F, E, D, A, B, and C - that's six channels, i.e. 384 (um, actually 432) bit wide access to memory.
Adding another six DIMMs enables no more channels, but now the processor can switch between DIMM 1 and DIMM 2 in each channel. (This is the same idea as dual rank modules.) Presumably it can issue a command to DIMM 1, then toggle over to DIMM 2, and then return to DIMM 1 where the command has completed.
yea this is very confusing... I got my machine and saw this- on the machine it has the diagram for 10 dimms but in the manual they clearly state only 4/6/8/12 is supported..
I went ahead and installed 2x8 in channel one and then the other 6 in channels 2,4,5 as per the manual.
when I booted, the orange light was blinking and the machine didn’t start..
not sure what happened, maybe a dumm was loose or something.
i went ahead and removed the 8 gigs for now and just put my 6 dimms, and now it works.
I’m gonna test the 8 and 10 dimm config later, but it would be great if someone could point me towards a benchmark for ram.
for now I’m having trouble getting my two Dell 5k displays to work, so far only one shows a signal...
Did you have to reset NVRAM or did the RAM update just work natively?
==
Is this what happened? ~
The Mac Pro supports both R-DIMMs and LR-DIMMs, but you can't mix these two memory types. Mixing R-DIMMs and LR-DIMMs will result in a memory error flash of the status indicator light when you turn on your computer.
==
Where does it say in the manual the Mac Pro allows 10 configuration? Can you take a pic and post?
DIMM configurations of 5, 7, 9, 10, and 11 DIMMs are not supported. Other configurations of 1, 2, and 3 DIMMs are for diagnostic use only.
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In the manual it doesn't say that 10 dimms are supported, but on the phyiscal ram enclosure on the machine on the inside there is a pictogram, showing a 10 dim configuration. Dont want to open up the machine right now because everything is installing, but it's there.
About LR-Dimms and R-Dimms, not sure, as my new dimms are R-Dimms, and I suppose the preinstalled 8Gb dimms are as well.. I can't find anything if I google the Part Number that is on the preinstalled memory:
MTA9AsF1G72PZ-2G9E6VG
No problems here. My 16 core Mac Pro arrived this morning - tested it out first with the stock 32GB and then put in the 384GB of Samsung memory I got from memory.net. All working perfectly so far!
Good info .
Here's the make and model info . $288 per module . 6 x 64GB ( 384 GB ) :
M386A8K40CM2-CVF - Samsung 1x 64GB DDR4-2933 LRDIMM PC4-23466U-L Quad Rank x4 Module .
Remember to reset your NVRAM now for improved performance and stability .
I tried again to insert two of the old 8 gb sticks together with the new 6x32gb, and again, the orange light of doom was blinking, so the sticks weren't loose but I made some other mistake.
The green ones are new, the black ones original.
I started with the small 2x8gb in Channel 1 and then distributed the others in channels 2,4,5 like the manual suggests.
What am I doing wrong here?
I'm considering getting an additional 2x8gb to fill all slots but first of all I can't seem to find fitting 8gb 2933mhz dimms, and secondly, I'm wondering if they will work together at all.
Honestly I also think that 192gb are enough for me, but well.
![IMG_2018.jpeg]( "IMG_2018.jpeg")
![IMG_2021.jpeg]( "IMG_2021.jpeg")
The green ones are new, the black ones original.
I started with the small 2x8gb in Channel 1 and then distributed the others in channels 2,4,5 like the manual suggests.
What am I doing wrong here?
I'm considering getting an additional 2x8gb to fill all slots but first of all I can't seem to find fitting 8gb 2933mhz dimms, and secondly, I'm wondering if they will work together at all.
Honestly I also think that 192gb are enough for me, but well.
Are you mixing LR-DIMMs and R-DIMMs in the same System ? That's not permitted .
The physical installation looks OK .
Here's Apple's advice on installing different size modules in the same System :
Installing DIMMs of mixed capacities
If your DIMMs are different capacities (like four 16GB DIMMs and four 32GB DIMMs), they must be installed according to these requirements:
Install DIMMs in order of the channels.
Install DIMMs in identical pairs for each channel.
Install DIMMs in order of smallest to largest capacity.
Use only R-DIMMs or only LR-DIMMs.
How to install DIMMs of mixed capacities
Find out which slots to use for your DIMM configuration.
Starting with the lowest capacity pair of DIMMs, install your DIMMs in identical pairs from smallest to largest capacity in order of the memory channels:
Channel 1: Slots 5 and 8
Channel 2: Slots 3 and 10
Channel 3: Slots 1 and 12
Channel 4: Slots 6 and 7
Channel 5: Slots 4 and 9
Channel 6: Slots 2 and 11
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No I’m not mixing LR with R dimms, except if the Apple dimms that came with the system were LR dimms, which would be strange- I don’t know how to find out if they are or not?
My understanding is that they use the LR dimms only for very high configurations.
yea thanks for that post, that was what I used to place them as well..
My MP7,1 came with 32GB ( 4 x 8 GB ) . Hynix Part Number : HMA81GR7CJR8N-WM . They are registered DIMMs ( R DIMM ) .
Just a note about OWC/Macsales...they will replace not one, but ALL the memory sticks in your computer if any of them stop working or throw errors, for the lifetime of your computer. I had a single memory stick stop working causing kernel panics on my 5,1 only a few years in and they replaced all of it at no cost. To me it is a no-brainer to buy from them, but does anyone know if those other 3rd-party options offer the same warranty guarantee?
Try putting the 32's in slots 1, 3, 5, 8, 10, and 12. Then put two 8's in 6 and 7.
Also, 32's in slots 1, 3, 5, 8, 10, and 12 with the four 8's in 4, 6, 7, and 9.