I'm looking to upgrade to about 96gb of ram from the default 32gb (4 x 8gb sticks). From reading different posts I'm hearing grouping 6-12 sticks has the best performance. Could I insert 2 x 32GB 2933MHz DDR4 PC4-23400 RDIMM with my current 4 x 8gb set up? I'm looking at OWC's 64gb, has anyone found a better deal? https://eshop.macsales.com/item/OWC/2933R3M64/ Appreciate it
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MP 7,1 Upgrading memory from stock 32gb
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Option 2 assuming your added sticks are exact match in performance to the Apple sticks specs. I would second OWC, but some guys here are recommending a cheaper Nemix RAM alternative which are being mislabeled as 2933MHz. So that scares me a bit about the true quality of their RAM.
This is discussed in other threads but the most important issue is to have 6 lanes filled (3 channel memory controller, two sticks wide). There are two sets, so, ideally the second set is empty or full.
In option 1, you're 6-wide for half the memory space (100% efficient), and 2-wide for the rest (2 of 6 is 33% efficient on memory access). In option 2, the whole memory space is 100% efficient—clearly the best, performance-wise.
Option 3 is to remove (and sell) 4 x 8GB, install 6 x 16 GB. Then you still have room to add another 6 x 16 GB in the future.
And just to add Option 3 is ideal if you know you will be expanding in the near future. If you know you will never expand or even need more than 96GB in the coming years, then you are at 95% efficiency with 6 DIMMs versus 100% efficiency at 12 x 8GB. In which case I'd rather be at 12 DIMMs populated all matched.
Look on ebay for other Mac Pro 7,1 owners that are selling their kits. I purchased 2 seperate 32gb kits from other owners that were upgrading their ram and I have 96gb in my 7,1 all for about $350.
So essentially, I have all my ram slots filled with OEM ram. Can't get any better than OEM.
So essentially, I have all my ram slots filled with OEM ram. Can't get any better than OEM.
Once I receive the "correct" DIMMs from Nemix (hopefully by Thursday after the last set was mislabeled), I will have my (4) original 8GB modules that I received in my new MacPro three weeks ago up for sale.
I admit my relative expertise in computer memory quite dated, so fill me in if I'm missing something. But this is a 3-channel memory controller. Why would 6 DIMMs be 95% efficient to 12's 100%?
Someone please take it!
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You mean 6 channel memory controller. All 6 channels have 12 dimm slots so you want to populate that fully in matched pairs to take advantage of it.
Here‘s an excerpt from a white paper done on this.
^^^^
Yes, of course I meant six channel (maybe my old 2009 Mac Pro brain cells engaged there?).
Thanks for the chart, I looked for exactly that info when I was figuring out the RAM details out, didn't find, but figured the difference would be small at best. And of course the 5% difference would be much less than that in actual use, but good to know.
Either way, getting 6 x16GB made sense for me at this time, while bing able to double it later on.
Yes, of course I meant six channel (maybe my old 2009 Mac Pro brain cells engaged there?).
Thanks for the chart, I looked for exactly that info when I was figuring out the RAM details out, didn't find, but figured the difference would be small at best. And of course the 5% difference would be much less than that in actual use, but good to know.
Either way, getting 6 x16GB made sense for me at this time, while bing able to double it later on.
Just received my replacement set of (6) 16GB modules from Nemix (first set was mislabeled). All looks good now...
Found info from the white paper that mentions mixing memory sizes in a balanced configuration (in which case they label as near-balance in this case):
"If DIMMS are populated on the memory channels such that they have different total memory capacities, the memory controller has to create multiple interleave sets. Some interleave sets could have fewer DIMMs. Managing multiple interleave sets creates overhead for the memory controllers, which can reduce memory bandwidth."
They further quantify the loss later in the paper:
"Measurements show about a 3% loss in memory bandwidth when using a Near-Balanced memory configuration as compared to a Balanced memory configuration as long as there are an even number of total memory ranks on each memory channel."
"If DIMMS are populated on the memory channels such that they have different total memory capacities, the memory controller has to create multiple interleave sets. Some interleave sets could have fewer DIMMs. Managing multiple interleave sets creates overhead for the memory controllers, which can reduce memory bandwidth."
They further quantify the loss later in the paper:
"Measurements show about a 3% loss in memory bandwidth when using a Near-Balanced memory configuration as compared to a Balanced memory configuration as long as there are an even number of total memory ranks on each memory channel."