There’s a ton of unnecessary speculation going on here regarding performance of different memory configurations. This paper does an excellent job of showing how any configuration other than 6 or 12 identical DIMMs can seriously harm your performance. If you’re feeling lazy at least look at the table on page 18.
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MP 7,1 Best RAM configuration for the 2019 Mac Pro
- Thread starter jasoncarle
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there's a clue in the description . "SR" and "DR" .
What is memory rank
The concept of memory rank applies to all memory module form factors, though in general it tends to matter primarily on server platforms, due to the larger amounts of memory they manage.
www.crucial.com
Memory rank - Wikipedia
From HPE for their Systems :
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Note that everything in that paper is based on the STREAM benchmark, a bandwidth virus that effectively disables caches. Good paper if STREAM is all that you run....
Applications will not see that dramatic an effect. See https://forums.macrumors.com/thread...ith-various-mem-configs.1704700/post-18745317 for a discussion of the Geekbench component tests with one/two/three/four DIMMs on an MP6,1.
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Just waiting for my 16C to arrive. Looking to utilise the 32gb factory default - and not overly throw money at it at the moment. Thinking about adding either 2 32gb or 2 64gb sticks. Based in the UK and apart from MacSales not really finding exact matches to the Samsung references in this post. Wonder if anyone had joy finding reasonably priced RAM in the UK?
Samsung seems to be the only one who makes a DDR4 2666 RDIMM for the 8-16 core Mac Pro, and so far I only see a 8GB RAM card...
You can use the 2933 MHz DIMMs - they'll be downclocked to 2666 on CPUs that don't support 2933.
Crucial has a number of them listed in their Server Memory section.
My brain hurts when shopping for RAM. Some sites specify compatibility with the MP others don't. Wonder if this is? https://uk.crucial.com/gbr/en/ct32g4rfd8293
It appears compatible to me so I would buy it. To be sure, contact their Sales Department and inquire. Crucial is good about returns if it doesn't work.
A question about RAM configurations in the new pro: I see a fair number of people installing different RAM sizes in the same 6 channels as the stock 32 GB, e.g. adding 2x16 or 2x32 along with the stock 4x8 GB sticks. Is there no performance penalty for doing so?
You could phone crucial...
I just spoke to someone at Mr Memory Uk
Apple Mac Pro Late 2019 - 3.2GHz 16-Core [Tower] Memory RAM Upgrades - FREE Delivery & Guaranteed Compatible | Mr Memory®
Buy Memory RAM Upgrades for your Apple Mac Pro Late 2019 - 3.2GHz 16-Core [Tower] - 100% Compatibility Guaranteed. ✅ FREE Delivery ✅ Low Prices ✅ 100% Safe & Secure
www.mrmemory.co.uk
I used to trust them but they don't actually tell you what memory you are going to get / manufacturer code on the site. But they did say they sell the Samsung units...
Samsung Server RAM 32GB 2933 MHz ECC RDIMM DDR4 Single Memory Module
Buy from Scan - 32GB (1x32GB) Samsung M393A4K40CB2-CVF DDR4 Server RAM, PC4-23400 (2933), ECC Registered, CAS 21, Dual Rank,1.2V
Mr Memory also implied that you can ONLY install 192GB of R-Dimms (16 core)... I think that is incorrect. Anyone?
LR-DIMMS are installed beyond 192gb as default by apple because the next step is 384gb
But I am fairly sure you can install 12 x 32gb R-Dimms? Right?
Basically we need someone clever (really not me) to set up a price watch of all the places USA/UK/Europe/Asia that actually sell the RIGHT ones
For UK buyers - the RAM mentioned above is the exact RAM I purchased from scan and can confirm working in my system.
www.scan.co.uk
Samsung Server RAM 32GB 2933 MHz ECC RDIMM DDR4 Single Memory Module
Buy from Scan - 32GB (1x32GB) Samsung M393A4K40CB2-CVF DDR4 Server RAM, PC4-23400 (2933), ECC Registered, CAS 21, Dual Rank,1.2V
From reading Apple's specs, it is my belief that you can use all RDIMMs if you wish, including using 64GB RDIMMs to exceed 384TB since they are becoming more readily available now.
There's a measurable penalty when mixing RAM sizes even when they are all 6 channels.
These are from my MacPro 7,1 Geekbench5:
- 48GB (6*8) Apple RAM: 19386 (https://browser.geekbench.com/v5/cpu/1064941)
- 192GB (6*32) Samsung: 20830 (https://browser.geekbench.com/v5/cpu/1065919)
- 240GB RAM (6x32 + 6x8): 18891
(https://browser.geekbench.com/v5/cpu/1066018)
I think the best perf is with 32GB modules, ideally 12 of them. Any mixing of size or not using the full channels result in perf lost, although for a lot of applications the difference is likely imperceptible. That being said I took out the 48GB I got with it and use only the 192GB I bought...
These are from my MacPro 7,1 Geekbench5:
- 48GB (6*8) Apple RAM: 19386 (https://browser.geekbench.com/v5/cpu/1064941)
- 192GB (6*32) Samsung: 20830 (https://browser.geekbench.com/v5/cpu/1065919)
- 240GB RAM (6x32 + 6x8): 18891
(https://browser.geekbench.com/v5/cpu/1066018)
I think the best perf is with 32GB modules, ideally 12 of them. Any mixing of size or not using the full channels result in perf lost, although for a lot of applications the difference is likely imperceptible. That being said I took out the 48GB I got with it and use only the 192GB I bought...
Crucial 16GB DDR4-2666 RDIMM
CT16G4RFD4266
Maybe??
www.crucial.com
Tried getting a confirmation from Crucial this would work, they would not... The person I was chatting with online said they have NO memory that will work with the Mac Pro 2018
CT16G4RFD4266
Maybe??
Crucial 16GB DDR4-2666 RDIMM | CT16G4RFD4266 | Crucial.com
Buy Crucial 16GB DDR4-2666 RDIMM CT16G4RFD4266. FREE US Delivery, guaranteed 100% compatibility when ordering using our online tools.
Tried getting a confirmation from Crucial this would work, they would not... The person I was chatting with online said they have NO memory that will work with the Mac Pro 2018
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I agree - I think Mr memory sales person just misunderstood due to what Apple sells... 384gb> is LRDimms.
From apple site
"8-core, 12-core, and 16-core Mac Pro models support up to 768GB of memory."
Does not specifically state that it has to be LRDimm beyond 192.
They are still Gouging the hell out of it. We need a CamelCamelCamel for Apple Ram!
I will test this configuration when I receive my MP7,1 between Feb 7-13 and post back here.
I have two 32Gb RAM sticks from Crucial working just fine in my 7.1Crucial 16GB DDR4-2666 RDIMM
CT16G4RFD4266
Maybe??
Crucial 16GB DDR4-2666 RDIMM | CT16G4RFD4266 | Crucial.com
Buy Crucial 16GB DDR4-2666 RDIMM CT16G4RFD4266. FREE US Delivery, guaranteed 100% compatibility when ordering using our online tools.
Tried getting a confirmation from Crucial this would work, they would not... The person I was chatting with online said they have NO memory that will work with the Mac Pro 2018
The difference is the top is SR x 4 and the bottom is DR x 8. This might help: https://www.speedguide.net/articles/choosing-ram-type-2778
[automerge]1579894863[/automerge]
Also, I have 6 x 64 GB Supermicro DIMMs from NewEgg that were more reasonable in cost than the latest prices from Nemix.
So nothing scientific here...but A mixed memory amount test. The Config is a little odd but explains it all on the apple site.
Geekbench with:
32GB - 4x8GB ( Original Sticks)
192GB - 6x32GB RAM (samsung from Scan UK - Listed in post #86 above)
and Both.
224GB 6x32GB + 4x8GB
in the correct (confusing) config
So a reasonable amount of performance more at 9.7% to NOT have the extra 32GB... Going on ebay and I'll buy another 192GB in the Future.
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