# DIMMs placement mixing sizes - Mac Pro 5.1



## motomuso (May 13, 2016)

Howdy,
I'm going to try adding two 16GB DIMMs to my Westmere Mac Pro 5.1 2 x 2.4 gHz Quad-Core (8-core) running OSX 10.9.5 Mavericks for 48GB RAM. (I'm also considering going to El Capitan but that's probably for another thread.) 
Currently running this...







... and I'm thinking to replace the two 4GB sticks with the 16s, then replace the next two 2GB with the 4GB I've just removed. I know the memory configurator will let me know if it's all in the correct places but now I'm reading (old) posts online about never mixing anything when using 8GB or 16GB sticks. This may be old news when it comes to 10.9 and above. I'm mainly using Kontakt 5.5.2 with Logic Pro X 10.2.2. 
(A slave computer is not in the budget at the moment but I am adding a 1TB SSD to an upper bay. PCI SSD is planned for the next paying job, hopefully.)

So the questions are: 
1. Has anyone been able to find a chart showing optimal placement for mixed DIMM sizes? 
2. Is this RAM configuration ill-advised? I may just pony up for another two 16GB sticks.

Thanks for the warm welcomes, This place is the ginchiest!
--
moto


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## higgs (May 13, 2016)

I just checked on OWC's page for Mac memory upgrades and there's this little disclaimer for the MacPro5,1 which is definitely the case for my Pro 6,1 cylinder:

_*16GB Module Sets require that all installed modules be of the same p/n OWC 16GB modules. 16GB modules do not mix with other density (1GB, 2GB, 4GB or 8GB) module types._​
I wish I had something better to report to you, but once you go over the 8gb RAM barrier, the Mac Pro's require installation of matched DIMM sizes. 

-- So essentially it's 16GB DIMMs with the other slots empty until you can mount another pair of 16's... ugh


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## higgs (May 13, 2016)

You don't have to take my word for it - they have online chat support which I believe is 24/7, and they're really great.


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## motomuso (May 13, 2016)

higgs said:


> You don't have to take my word for it - they have online chat support which I believe is 24/7, and they're really great.


Thanks higgs. I must have been over that page 12 times and did not see that little morsel. Well, the upside is that 64 beats 48 but I will double check with the chat. I had thought they were closed 'til tomorrow.


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## higgs (May 13, 2016)

motomuso said:


> Thanks higgs. I must have been over that page 12 times and did not see that little morsel. Well, the upside is that 64 beats 48 but I will double check with the chat. I had thought they were closed 'til tomorrow.


If you look in the section where they list 16 GB sticks, there is a little disclaimer that says "special note" and if you click that it actually explains this in slightly greater detail.


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## motomuso (May 13, 2016)

Two more sticks ordered. Now I hope that 4 x 16 isn't somehow slower than 8 x 8.


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## higgs (May 13, 2016)

motomuso said:


> Two more sticks ordered. Now I hope that 4 x 16 isn't somehow slower than 8 x 8.


Go for broke - order four more on top of the two! I'm running 64gb on the cylinder - kinda wish that I had started with the 32 GB sticks so that I could total at 128 GB without the need for completely replacing all 4 DIMM's. Such is life.

As far as speed is concerned with 4x16 vs. 8x8, that should not be an issue.


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## motomuso (May 13, 2016)

higgs said:


> If you look in the section where they list 16 GB sticks, there is a little disclaimer that says "special note" and if you click that it actually explains this in slightly greater detail.


Ah, well that teaches me to be more aware next time. Thanks again.
Somewhere I read that the usable top was 96GB on these machines though 128 is okay for running _Windows_? I dunno - I need to try to keep _some_ $$ left as I have Spitfire plans.


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## motomuso (May 13, 2016)

higgs said:


> Go for broke - order four more on top of the two! I'm running 64gb on the cylinder - kinda wish that I had started with the 32 GB sticks so that I could total at 128 GB without the need for completely replacing all 4 DIMM's. Such is life.
> 
> As far as speed is concerned with 4x16 vs. 8x8, that should not be an issue.



Looks like going for broke will happen eventually. This is from OWC regarding the 2009-2012 Mac Pros:

*"IMPORTANT OWC NOTE:
OS X versions prior to 10.9 Mavericks are unable to utilize more then 96GB RAM due to an operating system limitation. 128GB can be fully utilized by a 2009-2012 Mac Pro if running OS X 10.9 Mavericks or later, or if running Bootcamp with 64-bit versions of Windows XP and later, as well as with 64-bit versions of Linux."*


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## FriFlo (May 14, 2016)

higgs said:


> Go for broke - order four more on top of the two! I'm running 64gb on the cylinder - kinda wish that I had started with the 32 GB sticks so that I could total at 128 GB without the need for completely replacing all 4 DIMM's. Such is life.
> 
> As far as speed is concerned with 4x16 vs. 8x8, that should not be an issue.


I wouldn't be to sure about that ... I am not an expert by any means, but as far as I understand, each ram slot has its bandwidth and speed and using only half of the slots should mean only half of the bandwidth and speed. Just like it is better to use multiple SSDs where your samples are stored vs just one big SSD, no?


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## higgs (May 14, 2016)

FriFlo said:


> I wouldn't be to sure about that ... I am not an expert by any means, but as far as I understand, each ram slot has its bandwidth and speed and using only half of the slots should mean only half of the bandwidth and speed. Just like it is better to use multiple SSDs where your samples are stored vs just one big SSD, no?


I'm no expert on the issue either but maybe there are a couple of ways to look at it... My guess is that having more RAM - particularly for larger projects or templates - would be more efficient than purging and loading samples to accommodate a leaner memory pool. So in the workflow sense, it would objectively be 'faster,' right?


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## higgs (May 14, 2016)

And motomuso _is_ entertaining the possibility of throwing a lot of RAM at his tower.


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## motomuso (May 14, 2016)

higgs said:


> I'm no expert on the issue either but maybe there are a couple of ways to look at it... My guess is that having more RAM - particularly for larger projects or templates - would be more efficient than purging and loading samples to accommodate a leaner memory pool. So in the workflow sense, it would objectively be 'faster,' right?





higgs said:


> And motomuso _is_ entertaining the possibility of throwing a lot of RAM at his tower.



Oh whoops! Looks like I may have to be be going "all in". Ah well, we only live once and this line of work was never for the faint of heart anyway.


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## Rex282 (May 14, 2016)

motomuso said:


> Oh whoops! Looks like I may have to be be going "all in". Ah well, we only live once and this line of work was never for the faint of heart anyway.


 
uh ohh now you did it!! now your rig will be able to FLY!!!


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## motomuso (May 15, 2016)

Rex282 said:


> uh ohh now you did it!! now your rig will be able to FLY!!!


Hmm, let me think a minute - 64Gb more or Spitfire's Blasty-horns Bundle...


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