MP 7,1 PSA: Make sure you're using all 6 channels of ram or lose 10% cpu performance.

[RyanFlynn]

Hey friends,

Looks like there is about a 10% CPU performance jump going from the stock 32gb to 48gb using all 6 memory channels. My Geekbench 5 score went from the low 14 thousands to 15,800 on the 16core. Thats a great jump!

Ryan

 

[Korican100]

did you just add 2 8gb sticks? or replaced your stock ram altogether?

Also, can anyone chime in on using the full 12 slots, whether that will provide a hit on performance or not?

 

[Theophilos]

In a previous thread somewhere, one member said that using all 12 slots of matched memory would provide 100% memory bandwidth and using 6 slots of matched memory would provide 97% memory bandwidth. From what I gather, it seems important to:

1. Use matched DIMMs if possible
2. Have at least 6 DIMMs installed in appropriate pairs
3. Avoid mixing and matching different sizes in pairs (4 x 8 GB and 2 x 32 GB on the same machine, for example)

 

[zhpenn]

yes, the same finding here Geekbench 5
28 cores
with 4x32g+4x8g = 17000+
but 4x32g ONLY = 19XXX+
I'm buying 2x32g extra, will wait and see the result after I install it.

 

[Bradleyone]

yes, the same finding here Geekbench 5
28 cores
with 4x32g+4x8g = 17000+
but 4x32g ONLY = 19XXX+
I'm buying 2x32g extra, will wait and see the result after I install it.

While you're testing, maybe you could also do your multi-minute RAW files to JPEG test?

A real world example might add weight to the suspicion that some of these benchmark tests are skewing the actual effect of memory configs on day to day use.

 

[Coyote2006]

is there a greekbench difference between 6x 8GB and for example 6x32GB RAM?

 

[zhpenn]

is there a greekbench difference between 6x 8GB and for example 6x32GB RAM?

I think in GB should be the same, in real-world if you only use 10 GB of ram, it should be the same, but if you use more than 48GB of ram then the 6 x 32GB will win.

While you're testing, maybe you could also do your multi-minute RAW files to JPEG test?

A real world example might add weight to the suspicion that some of these benchmark tests are skewing the actual effect of memory configs on day to day use.

yea you are right, I may give it a try and see the result.

 

[RyanFlynn]

I've continued testing this

did you just add 2 8gb sticks? or replaced your stock ram altogether?

Also, can anyone chime in on using the full 12 slots, whether that will provide a hit on performance or not?

Just adding 2 more 8gb sticks from the stock config did the trick. I also added an additional 6x 32gb sticks, but couldn't get the computer to boot with all sticks of ram. Perhaps I had them in the wrong order?
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is there a greekbench difference between 6x 8GB and for example 6x32GB RAM?

in my geek bench tests, there was no difference between the 6x 8gb and 6x 32gb

 

[Coyote2006]

is the 8 core also 6 channel or only 4 channel?

 

[RyanFlynn]

Yeah looks like the 8 core is 6 channel as well, its just runs the ram at a slower clock speed, making the 12core upgrade a really good value all around.

Mac Pro (2019) memory specifications - Apple Support

Learn about the types of memory (RAM) used in Mac Pro (2019).

support.apple.com

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Looks like the only way to get maximum performance is to run 6 or 12 identical ram modules. I've seen as much as a 15% drop in CPU perforce running unbalanced configurations. If anyone as 32gb, be sure to get up to at least 48 via 2 more 8gb sticks

 

[profdraper]

Recently added 6 x 32gB sticks on Nemix Ram & replaced Apple's stock 32GB. Works like a charm & many apps & the OS are clearly much happier, snappier.

 

[bxs]

Recently added 6 x 32gB sticks on Nemix Ram & replaced Apple's stock 32GB. Works like a charm & many apps & the OS are clearly much happier, snappier.

That gives you 97% of the max performance which is very good IMO. 12x 32GB will provide the extra 3% making it 100%.

 

[RyanFlynn]

Recently added 6 x 32gB sticks on Nemix Ram & replaced Apple's stock 32GB. Works like a charm & many apps & the OS are clearly much happier, snappier.

Run geek bench 5 with the 10 sticks you have in there now, then run it with the 6 32gb and you’ll see about a 10% performance jump.

 

[bxs]

Run geek bench 5 with the 10 sticks you have in there now, then run it with the 6 32gb and you’ll see about a 10% performance jump.

It would be even more interesting to see the improved memory bandwidth in GBytes/sec. GeekBench 5 does not display this for memory but GeekBench 4 does.... or run STREAM benchmark on each RAM configuration to get a more precise measurement.

 

[RyanFlynn]

absolutely, but the fact that it actually contributes to cpu performance is incredible. With cpu performance, its better to have 192gb of balance memory than 224gb of unbalanced.

 

[majus]

Yeah looks like the 8 core is 6 channel as well, its just runs the ram at a slower clock speed, making the 12core upgrade a really good value all around.

When channels are filled with matching pairs, all of the various cores run at 2666MHz.

A few more comments here:

2933 MHz Memory. Really?

From the Apple Support Document, this: All memory included with your Mac Pro is 2933MHz. Mac Pro models with 8 core processors operate memory at 2666MHz. ... • Install DIMMs in identical pairs for each channel. ... From cpu-world.com's info on the W-3245 cpu, I find this: Notes on Intel Xeon...

forums.macrumors.com

 

[bxs]

When channels are filled with matching pairs, all of the various cores run at 2666MHz.

A few more comments here:

2933 MHz Memory. Really?

From the Apple Support Document, this: All memory included with your Mac Pro is 2933MHz. Mac Pro models with 8 core processors operate memory at 2666MHz. ... • Install DIMMs in identical pairs for each channel. ... From cpu-world.com's info on the W-3245 cpu, I find this: Notes on Intel Xeon...

forums.macrumors.com

If that's the case then the memory display will or should indicate this... !?

 

[chfilm]

This is true, I noticed a drop about 2000 points when I went from 6 to 10 sticks. (Yes, 10 worked!)

 

[RyanFlynn]

Yeah I went with 10 sticks, And even 12 sticks but with a symmetrical quantities, and saw a significant performance drops in both Premier render times and benchmarks.

 

[bxs]

When channels are filled with matching pairs, all of the various cores run at 2666MHz.

A few more comments here:

2933 MHz Memory. Really?

From the Apple Support Document, this: All memory included with your Mac Pro is 2933MHz. Mac Pro models with 8 core processors operate memory at 2666MHz. ... • Install DIMMs in identical pairs for each channel. ... From cpu-world.com's info on the W-3245 cpu, I find this: Notes on Intel Xeon...

forums.macrumors.com

Can you take a screen shot of the MP7,1's memory display that shows 2666MHz when all 12 slots are populated with same size DIMMs ? I assume this would be for a MP7,1 with 12cores or higher, right? Thanks...

 

[RyanFlynn]

Can you take a screen shot of the MP7,1's memory display that shows 2666MHz when all 12 slots are populated with same size DIMMs ? I assume this would be for a MP7,1 with 12cores or higher, right? Thanks...

It won’t show that. It will run at 2933

 

[bxs]

It won’t show that. It will run at 2933

Thanks... was confused with what majus posted above.

 

[majus]

Thanks... was confused with what majus posted above.

Honestly, I am not confused; I can read. Please go to the thread I linked and read it for yourself. It says what it says about the W-32xx series CPUs.
• Maximum DDR4 memory frequency is for 1 DIMM per channel configuration. When 2 DIMMs per channel are populated, the memory runs at 2666 MHz

That note does not apply to the 8-core because the W-3223 does not specify that.

 

[bxs]

Honestly, I am not confused; I can read. Please go to the thread I linked and read it for yourself. It says what it says about the W-32xx series CPUs.
• Maximum DDR4 memory frequency is for 1 DIMM per channel configuration. When 2 DIMMs per channel are populated, the memory runs at 2666 MHz

That note does not apply to the 8-core because the W-3223 does not specify that.

My enquiry is - does the 2666 MHz show up in any display offered in the MP7,1 to confirm this ?

The best way for determining memory bandwidth regardless of the DIMM's MHz setting is to use STREAM Triad. For the MP7,1 this STREAM Triad result will be at a maximum when all 12 DIMM slots are filled with identical sized DIMMs.

 

[zhpenn]

It really faster in real life when doing LR export! unbelievable!
check this out

4 VS 6 channels RAM in Real-world Lightroom TEST! It is 39.2% FASTER?! [UPDATE RAMDISK TEST]

I know when I upgrade from 4 channels to 6 channels will have about 10% Geekbench scores increase! BUT will it make a difference in real life? In short YES, and HUGE! Geekbench 5 scores: CPU: 28-Cores 3275M RAM: 4x32g + 4x8g = 17638 4x32g ONLY = 19360 (increase by 9.76%) 6x32g ONLY = 20979...

forums.macrumors.com