Mac Pro 128GB RAM

Hello,

I have just upgraded my Mac Pro to 128GB RAM, and although the system recognizes it all (in "about this Mac") I can use only 96GB (which is what I see in Activity Monitor).

I use Snow Leopard, and I was wondering if you know of any way around it so I could use all 128GB.

Many thanks for any suggestion.

By design your Mac Pro will only use 96 GB regardless of what it "sees". (Mactracker says 96 GB while Apple says 64 GB.) BTW, that's for the Quad Core.

96gb is probably all that your machine can handle.

uv2012 said:

Hello,

I have just upgraded my Mac Pro to 128GB RAM, and although the system recognizes it all (in "about this Mac") I can use only 96GB (which is what I see in Activity Monitor).

Click to expand...

Need to know exactly which model Mac Pro you have. As pointed out already...quad-core Mac Pros have a lower max ram than the 8-core models.

8-core Mac Pro models since 2009 are capable of 128gig of ram...so we need to know what you have.

- Nick

Thanks for your reply. I have a 12 core (two 6 core 2.93GHz) Mac Pro. I have also just noticed that perhaps the computer can use only about 60GB RAM since once the 60GB exceeds it goes to the swap (but I need to double check this one). Seems very odd to me.

I wanted to update my earlier post (did some additional research). Apparently 8-core Mac Pro's (since 2009) have a max ram limit of 96 gig of ram when running the Mac OS. If running a 64-bit version of Windows...then the max. ram that can be used is 128gig.

Quote from Everymac.com:

"*Apple officially supports 32 GB of RAM in this model, but as first noted by OWC, it actually could support 64 GB of RAM. Later, OWC bumped this unofficial maximum RAM to 96 GB running Mac OS X 10.6 or 10.7, and yet again to 128 GB, but only when running a 64-bit version of Windows XP or later or Linux. Mac OS X only can support 96 GB of RAM."

So 96gig max for the Mac OS...128gig max for 64-bit Windows OS or Linux.

- Nick

What could you possibly need 128 GB of RAM for? Unless you're running a VM warehouse in that thing.

I was wondering that too. Makes my machine look like a prototype abacus.

pigoo3 said:

Quote from Everymac.com:

"*Apple officially supports 32 GB of RAM in this model, but as first noted by OWC, it actually could support 64 GB of RAM. Later, OWC bumped this unofficial maximum RAM to 96 GB running Mac OS X 10.6 or 10.7, and yet again to 128 GB, but only when running a 64-bit version of Windows XP or later or Linux. Mac OS X only can support 96 GB of RAM."

So 96gig max for the Mac OS...128gig max for 64-bit Windows OS or Linux.

- Nick

Click to expand...

It's interesting that this is the case. It would seem that Apple has set an artificial limit on memory recognition. According to this blog:

Current Mac OS X versions are unable to utilize more then 96GB RAM due to an operating system limitation. 128GB can be fully utilized by a 2009-2010 Mac Pro if running Bootcamp with 64-bit versions of Windows XP and later as well as with 64-bit versions of Linux.

Click to expand...

I would imagine that this isn't an issue for 99.9% of Mac users however.

Thank you for all your replies. Since this is not a hardware problem do you expect there will be a software update that would allow using the whole 128GB on a Mac OS X?
The 128GB RAM (or shall we say 96GB) is for scientific purposes: analyses of several genomes simultaneously, each takes about 5GB RAM. So using all 24 threads could have been perfect, although 16 (to which I'm restricted now because of the 96GB issue) does the job quite well.

I doubt it will be changed with Lion. It's possible that this limitation will be removed from Mountain Lion but it's hard to speculate at this point.

uv2012 said:

Thank you for all your replies. Since this is not a hardware problem do you expect there will be a software update that would allow using the whole 128GB on a Mac OS X?
The 128GB RAM (or shall we say 96GB) is for scientific purposes: analyses of several genomes simultaneously, each takes about 5GB RAM. So using all 24 threads could have been perfect, although 16 (to which I'm restricted now because of the 96GB issue) does the job quite well.

Click to expand...

Technically speaking...Apple "officially" claims that max. ram on your Mac Pro is 32gig...so being able to install 96gig (3x official max.) is a BIG BONUS! This sort of thing (being able to install more ram than Apple claims) does happen from time to time.

Generally speaking...Apple (years later) doesn't usually release any sort of software updates that improves a systems capabilities (especially when it's related to hardware (in this case being able to install a higher max. ram)...but it has happened.

For example...a Mac Pro from say 2008 (which has TRUE max. ram of 32gig)...most likely will never be able to install 64 or 96 gig of ram (or any amount more than 32gig). I'm not saying it's 100% impossible...just unlikely.

- Nick

That's what I suspected... Now the big aesthetic dilemma - whether I should defect for Ubuntu on the Pro or keep the 96GB on my pretty OS X. Probably option 2, there is a limit for the sacrifices one can do for the sake of science