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monkeybagel

macrumors 65816
Original poster
Jul 24, 2011
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I have been running 128GB of RAM in various OSs on a 2012 Mac Pro. Although any OS X version before 10.9 does not support more than 96GB, it does not seem to compromise system stability. It does know the system has 128GB, however will use 96GB in Activity Monitor. Windows variants in 64-bit versions also work fine.

Just wanted to post this in the event anyone was considering the upgrade...
 

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Umbongo

macrumors 601
Sep 14, 2006
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England
Hope you will be able to update this when 10.9 comes out to confirm that it was just an OS issue and older Mac Pros will get full 128GB support with future OSes.
 

JavaTheHut

macrumors 6502
Aug 15, 2010
334
1
A question to the OP

Could you confirm or deny that you can create a RAM drive with the spare 32GB, there by leaving the remaining 96GB for the OS to address.

Thx
J
 

comatory

macrumors 6502a
Apr 10, 2012
738
0
I have been running 128GB of RAM in various OSs on a 2012 Mac Pro. Although any OS X version before 10.9 does not support more than 96GB, it does not seem to compromise system stability. It does know the system has 128GB, however will use 96GB in Activity Monitor. Windows variants in 64-bit versions also work fine.

Just wanted to post this in the event anyone was considering the upgrade...

damn! you must be using 8x16GB sticks am I right? expensive! i'm a "prosumer" so i don't really have use for such an amount but i bet you make use of it :)

anyway i had just a thought for some old timers. when do you think 128GB will be "new 4GB" seems like this amount is huge but I remember having 1GB in my PC rig in 2004 and it was considered a bigger amount.

5-8 years from now?

EDIT: just looking at this in Mactracker: dual USB iBook 2001 model had 64 megs when shipped. the same model had stock 512 megs in 2005, that's 8x in 4-5 years. 8 gigabytes are "good" standard now which would mean that by 2018, stock config will use 64GB.
 

monkeybagel

macrumors 65816
Original poster
Jul 24, 2011
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Hope you will be able to update this when 10.9 comes out to confirm that it was just an OS issue and older Mac Pros will get full 128GB support with future OSes.

This seems to be the case.
 

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monkeybagel

macrumors 65816
Original poster
Jul 24, 2011
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damn! you must be using 8x16GB sticks am I right? expensive! i'm a "prosumer" so i don't really have use for such an amount but i bet you make use of it :)

anyway i had just a thought for some old timers. when do you think 128GB will be "new 4GB" seems like this amount is huge but I remember having 1GB in my PC rig in 2004 and it was considered a bigger amount.

5-8 years from now?

EDIT: just looking at this in Mactracker: dual USB iBook 2001 model had 64 megs when shipped. the same model had stock 512 megs in 2005, that's 8x in 4-5 years. 8 gigabytes are "good" standard now which would mean that by 2018, stock config will use 64GB.

I think it would be several years, but any leap in technology could change that.

I recall a similar moment when I upgraded a Pentium MMX machine (Sony VAIO PCV-90) to 128MB from 32MB. Well above the standard norm but it was used and nice to have. That was many, many years ago.

----------

A question to the OP

Could you confirm or deny that you can create a RAM drive with the spare 32GB, there by leaving the remaining 96GB for the OS to address.

Thx
J

I will check and see. I would think that anything below OS X 10.9 will probably deduct it from the 96GB.

10.9 also displays the correct DIMM population as well.
 

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monkeybagel

macrumors 65816
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Jul 24, 2011
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Only ECC Registered Mac Pro specific 16GB sticks I've heard of are Mushkin's... but check the reviews:

http://www.newegg.com/Product/Product.aspx?Item=N82E16820226350

... doesn't seem to work.

OWC has 16GB modules but they aren't registered.

Standard DDR3 1333 ECC Registered memory will work of course, but won't it make the Mac Pro's fans run high since they lack the Apple thermal sensor?

These are Hynix modules and they do not make the fans run high at all. The machine is as quiet as it was with the original 12GB. There are 16GB ECC Registered CL9 DIMMs.

I normally purchase Crucial RAM based on a good track record with them, however Hynix is good OEM RAM and seemed to be a good choice when seeing what is available. Hynix was the OEM for the original 12GB.
 

flowrider

macrumors 604
Nov 23, 2012
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2,958

OrangeSVTguy

macrumors 601
Sep 16, 2007
4,127
69
Northeastern Ohio
I'm just running a single 16GB but Kingston and it works great and I get no fan noises etc. It's only 1066mhz ECC tho. I only have a quad so I got 4 total slots and are only good for 48GB I've read, I don't think 64GB works in the quads? And yes, RAM disks are incredibly fast!
 

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Umbongo

macrumors 601
Sep 14, 2006
4,934
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England
I'm just running a single 16GB but Kingston and it works great and I get no fan noises etc. It's only 1066mhz ECC tho. I only have a quad so I got 4 total slots and are only good for 48GB I've read, I don't think 64GB works in the quads? And yes, RAM disks are incredibly fast!

Yeah 64GB not working in the single CPU systems is what made me wonder if it wasn't more something to do with how the OS was interacting with the "odd" memory configuration you get with a full populated single CPU Mac Pro. They should be able to address 64GB with 10.9 if the dual systems can address 128GB.
 

monkeybagel

macrumors 65816
Original poster
Jul 24, 2011
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Yeah 64GB not working in the single CPU systems is what made me wonder if it wasn't more something to do with how the OS was interacting with the "odd" memory configuration you get with a full populated single CPU Mac Pro. They should be able to address 64GB with 10.9 if the dual systems can address 128GB.

According to these folks, which I tend to trust with their testing and experience with Macintoshes, the maximum on a single core is indeed 48GB no matter the DIMM configuration.

http://eshop.macsales.com/shop/memory/Mac-Pro-Memory#1333-memory

On the dual processor model, it does have a footnote explaining that 128GB is only available using 10.9 or Windows x64. I was concerned that the additional RAM would causing paging problems or other issues in versions of OS X that do not support 128GB, which right now is every other version of OS X except 10.9, but that does not seem to be the case.

I will say that I am running the current beta of 10.9 with VMware Fusion 6 Professional, nesting ESXi with 64GB of RAM as well as two other administration machines running natively in ESXi; Windows 7 Enterprise x64 and Windows 8.1 Enterprise x64. They are extremely responsive, have 8CPUs each, and 16GB of RAM. I have yet to see any slowdowns or page outs of any kind. I must say I am very pleased and impressed at how stable it is.

I could boot ESXi 5.1 directly from USB and make an internal SATA disk the VMFS volume, but since it is not for production VMs, the nesting works well to test the advanced features of VMware vSphere.
 

matthewtoney

macrumors regular
Aug 17, 2009
183
1
Charlotte, NC
Ugh!

Yeah 64GB not working in the single CPU systems is what made me wonder if it wasn't more something to do with how the OS was interacting with the "odd" memory configuration you get with a full populated single CPU Mac Pro. They should be able to address 64GB with 10.9 if the dual systems can address 128GB.

*Man* do I feel like a moron now. :(

I knew all about the 96GB limit but nothing at all about the 48GB limit for single processor machines. I've been running 3 of these in a 48GB config in my 5.1 w/W3690 for a good 8 months and I *just* ordered an additional one and it arrived yesterday - guess it is not gonna work...

Oh well, my own fault for not making absolutely certain I suppose

http://www.amazon.com/gp/product/B008542CTA/ref=oh_details_o04_s00_i00?ie=UTF8&psc=1
 

Umbongo

macrumors 601
Sep 14, 2006
4,934
55
England
*Man* do I feel like a moron now. :(

I knew all about the 96GB limit but nothing at all about the 48GB limit for single processor machines. I've been running 3 of these in a 48GB config in my 5.1 w/W3690 for a good 8 months and I *just* ordered an additional one and it arrived yesterday - guess it is not gonna work...

Oh well, my own fault for not making absolutely certain I suppose

http://www.amazon.com/gp/product/B008542CTA/ref=oh_details_o04_s00_i00?ie=UTF8&psc=1

It could well work with Mavericks, that could be something they have fixed too. Worth popping a version on disk and seeing before you send it back.

Although the problem could have been the single CPU models never being expected to address more than 48GB (6x8GB) as RDIMMs aren't supported by Intel for them rather than the triple-channel/4 slot configuration being weird with that much memeory.
 
Last edited:

crjackson2134

macrumors 601
Mar 6, 2013
4,823
1,948
Charlotte, NC
It could well work with Mavericks, that could be something they have fixed too. Worth popping a version on disk and seeing before you send it back.

Although the problem could have been the single CPU models never being expected to address more than 48GB (6x8GB) as RDIMMs aren't supported by Intel for them rather than the triple-channel/4 slot configuration being weird with that much memeory.

Pretty sure it won't work. Otherwise it would be reported that 64GB can be seen by other OS's. I was going to do the same thing until I found out from others on this form, that adding the additional DIMM would cause a boot fail.
 

Umbongo

macrumors 601
Sep 14, 2006
4,934
55
England
Pretty sure it won't work. Otherwise it would be reported that 64GB can be seen by other OS's. I was going to do the same thing until I found out from others on this form, that adding the additional DIMM would cause a boot fail.

Ah okay then it could be those CPUs never having been designed for more than 48GB.
 

matthewtoney

macrumors regular
Aug 17, 2009
183
1
Charlotte, NC
Pretty sure it won't work. Otherwise it would be reported that 64GB can be seen by other OS's. I was going to do the same thing until I found out from others on this form, that adding the additional DIMM would cause a boot fail.

Exactly - saw the post on here somewhere where OWC thought it would work as well (in Mavericks) until they tried it with their DIMMs and it wouldn't boot at all with 64GB in the single CPU model. I expect my experience will be exactly the same but we'll see.
 
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