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27" Retina iMac supports 64gb RAM?

dcmontgomery

dcmontgomery

macrumors member
Original poster
Oct 13, 2015
57
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Hello. Long time lurker, first time poster. Been waiting for a long time for new iMacs to come out to replace my 2009 Mac Pro.

I've read on a few posts, but nothing in detail, that the new 27" Retina iMacs support 64GB of RAM even though the Apple store only allows you to upgrade to 32GB.

So is this true? If I were to purchase a model with the base amount of RAM, could I buy 64GB of RAM from a 3rd party? OWC, Crucial? If so, who would you recommend and would that type of RAM be available anytime soon?

Thanks in advance!
 
I think Skylake supports DDR4. Too bad they didn't up to that spec though I guess.
 
So you're saying Skylake supports 64GB, but the new Retina iMacs still use DDR3 meaning 64GB is not possible? Sorry if these are dumb questions. I'm looking to buy an iMac soon and max out the RAM so I'd like to know if the max is 32 or 64. Thanks!
 
Last edited:
redheeler said:
Last year's Retina iMac actually supports running 1866 MHz DDR3 RAM at native speed, so they really changed nothing. I too am surprised they didn't include support for DDR4 on a Skylake iMac.
Click to expand...
Even the late 2013 non Retina supports 1866MHz memory ;)
The memory controller is in the CPU. Haswell CPU (late 2013 gen) can handle 2400MHz RAM modules (the fastest SODIMM RAM DDR3 RAM is 2133MHz though).
201510_1866MHz.png

As the memory controller is still in the CPU and as DDR3 and DDR4 SODIMM modules have the same connectors, I wouldn't be surprised the last iMac supports DDR4 modules...
 
dcmontgomery said:
Hello. Long time lurker, first time poster. Been waiting for a long time for new iMacs to come out to replace my 2009 Mac Pro.

I've read on a few posts, but nothing in detail, that the new 27" Retina iMacs support 64GB of RAM even though the Apple store only allows you to upgrade to 32GB.

So is this true? If I were to purchase a model with the base amount of RAM, could I buy 64GB of RAM from a 3rd party? OWC, Crucial? If so, who would you recommend and would that type of RAM be available anytime soon?

Thanks in advance!
Click to expand...
This is correct. It makes me wonder though why Apple didn't try to cash in on that though.
https://www.macrumors.com/2015/10/13/27-inch-imac-supports-64-gb-ram/
 
Woohoo! Looks like 64GB is a reality. Is Crucial offering 64GB kits for the new iMacs now? And if I wanted to pick some up, can anyone point me in the right direction or at least offer me some guidance on finding compatible memory. Thanks!
 
I guess I'm wondering about the cost/benefit ratio of upgrading to 64GB of RAM, assuming it's possible in the new 27" iMacs. My gut tells me that unless you are rendering video or graphics there won't be much of a performance gain. My gut also tells me that a 64GB RAM kit will be quite expensive.

EDIT: Just looked and OWC will sell the 64GB RAM kit for $1,195. I very much doubt anyone will see enough benefit from it to justify the cost.
 
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Video, graphics and photo editing will be the primary workloads on this machine. As someone who is typing on an eight year old Mac Pro, I don't mind paying more upfront to make the machine last longer as I don't upgrade or change machines often.

I can't imagine Crucial being near $1,200 for 64GB, but maybe I'm wrong. I thought OWC prices were at a significant premium over what Crucial sells their chips for.
 
Crucial's compatibility checker says those chips are not compatible with the late 2015 iMacs. Is that because they have yet to do testing so all chips fall under the "non-compatible" moniker? I assume the specs from the chip you linked to would work, but before I drop a lot of monies, I just want to be sure. I suppose Crucial will be releasing compatibility data for their memory regarding these new iMacs soon?
 
if you get 64gb of ram, why not getting a mac pro?
it's probably a little more expensive, but you'll have a better overall gpu+cpu & other components instead of just 64gb of ram?
or did the ram price just drop overnight?
 
Even with the 64GB upgrade, it's cheaper than buying a Mac Pro, adding 64GB in RAM in aftermarket then having to go out and buy a 5K monitor. I know I don't NEED 5k, but it's really nice to have and since I'm coming from a nine year old machine, my goal is to make this last a long time so I want to have 5k now so I'm at least on par with things as screens progress to the 4k/5k levels as normal down the road.

I also like the idea of the all-in-one as I'm really trying to reduce clutter. The back of my current Mac Pro and Cinema Display looks like a rat's nest of cords and power blocks.
 
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dcmontgomery said:
Crucial's compatibility checker says those chips are not compatible with the late 2015 iMacs. Is that because they have yet to do testing so all chips fall under the "non-compatible" moniker? I assume the specs from the chip you linked to would work, but before I drop a lot of monies, I just want to be sure. I suppose Crucial will be releasing compatibility data for their memory regarding these new iMacs soon?
Click to expand...
Yes, I believe this is probably incorrect. I am surprised they would update their site to mention it at all this soon.
 
dcmontgomery said:
Even with the 64GB upgrade, it's cheaper than buying a Mac Pro, adding 64GB in RAM in aftermarket then having to go out and buy a 5K monitor. I know I don't NEED 5k, but it's really nice to have and since I'm coming from a nine year old machine, my goal is to make this last a long time so I want to have 5k now so I'm at least on par with things as screens progress to the 4k/5k levels as normal down the road.

I also like the idea of the all-in-one as I'm really trying to reduce clutter. The back of my current Mac Pro and Cinema Display looks like a rat's nest of cords and power blocks.
Click to expand...
AFAIK the price difference between 4x16GB RDIMMs (that the Mac Pro uses) and 4x16GB UDIMM/SO-DIMMs (which the new iMac can use) seem to be $300-400 I think. The UDIMMs are more expensive as they have to use 8Gbit chips.
 
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