iMac Pro and 256GB

[mreg376]

OWC/macsales.com sells (and installs) a 128GB upgrade for the iMac Pro using either an additional two 32 GB modules, or replaces your current memory with two 64GB modules, saying that 4x64GB is not currently supported but you can get 2x64GB now just in case "Apple removes the 128GB limitation in the future." Is this realistic?

 

[DeltaMac]

Would Apple remove the 128GB limitation in the future?
Apple has done this in the past, although the last time I can remember is a firmware update for iMac G3 so that each slot would recognize larger RAM capacity. But, that was just a result, and Apple (AFAIK) never updated their own specs to show that more RAM could be installed. This is the usual thing that Apple does with memory. Third-party tests with more memory to find out what actually works, but Apple usually does not offer that information.
Bottom line - could Apple change the limit through either a firmware update, or a release of different chipset, therefore allowing for more RAM capacity? Maybe. But, Apple is unlikely to update their own released specs, unless they announce a new iMac Pro model with that updated hardware.

 

[Bryan Bowler]

Slightly off-topic, but it's hard to believe that in 5-6 years time, some of us will be putting 1TB of RAM in our machines.

 

[alien3dx]

Slightly off-topic, but it's hard to believe that in 5-6 years time, some of us will be putting 1TB of RAM in our machines.

by that time, everyone will push in virtual ram instead of SSD. ** Old time ram can be extra, so virtual ram exceed such as fast testing,scratch disk and so so on.

But current development kinda odd, old time memory are precious so memory are important . These day we spoil with ram and developer to used whatever resource ram as much as possible so operating system can cope with it. Some junior will think "if not used ,it's useless "

 

[cwanja]

I was actually looking to see if the current iMac models recognized 128GB of RAM up from 64GB.

I would say that it could eventually be supported, but you will not stumble across it announced.

 

[mreg376]

I still have a 2007 iMac. It officially supported only 4GB of RAM, but takes and uses 6GB. Apple never admitted it, but on the other hand it was like that from the beginning, so Apple did nothing after release to allow it.

OWC/macsales is pretty good at testing the limits of Macs, so I have a feeling that if the 2017 iMacs could support 128GB we would know it by now. So I'm not sure why OWC thinks that the RAM max for the iMac Pro might somehow change in the future, unless they believe that the hardware supports 4x64 now and Apple is actually limiting it in Mac OS.

 

[mj_]

The 64GB limit isn't imposed by Apple, it's the maximum the CPU's memory controller can handle.
According to Intel specs, the Kaby Lake desktop CPUs used in the current iMac only support up to 64GB max. See for example here: https://ark.intel.com/products/97123/Intel-Core-i5-7500-Processor-6M-Cache-up-to-3_80-GHz

The iMac Pro's Xeons support up to 512GB though so that 128GB limit is all Apple.

 

[mreg376]

The 64GB limit isn't imposed by Apple, it's the maximum the CPU's memory controller can handle.
According to Intel specs, the Kaby Lake desktop CPUs used in the current iMac only support up to 64GB max. See for example here: https://ark.intel.com/products/97123/Intel-Core-i5-7500-Processor-6M-Cache-up-to-3_80-GHz

Yes, that makes sense. Which is why I'm surprised that OWC, usually very knowledgable, offers to upgrade the iMac Pro with 2x64 so that the other two memory slots can be left free in case "the 128GB memory limit is removed by Apple." :

 

[mj_]

Because it's the iMac Pro with Xeon-W CPUs.

Again:

• The iMac is limited to 64GB by Intel's Kaby Lake CPUs in hardware.
• The iMac Pro is limited to 512GB by Intel's Xeon-W CPUs in hardware and to 128GB by Apple in firmware.

Should Apple in theory decide to lift that limit to 256GB or more, or should someone write a firmware hack to allow for more RAM, more than 128GB could be possible in the future. That's why OWC offers 2x 64GB for possible future upgrades, but they specifically state that a) 4x 64GB is not supported by Apple at this time, and b) it could be one day removed by Apple.

 

[Guy Clark]

I still have a 2007 iMac. It officially supported only 4GB of RAM, but takes and uses 6GB. Apple never admitted it, but on the other hand it was like that from the beginning, so Apple did nothing after release to allow it.

OWC/macsales is pretty good at testing the limits of Macs, so I have a feeling that if the 2017 iMacs could support 128GB we would know it by now. So I'm not sure why OWC thinks that the RAM max for the iMac Pro might somehow change in the future, unless they believe that the hardware supports 4x64 now and Apple is actually limiting it in Mac OS.

That is quite often the case as with the mid 2011 21.5" iMac. According to Apple the maximum amount of RAM is 16GB when in fact it can be maxed out at 32GB.
Also worth bearing in mind 32GB RAM from a manufacturer such as Crucial is cheaper to purchase than 16GB Apple RAM.

 

[mpe]

OWC/macsales.com sells (and installs) a 128GB upgrade for the iMac Pro using either an additional two 32 GB modules, or replaces your current memory with two 64GB modules, saying that 4x64GB is not currently supported but you can get 2x64GB now just in case "Apple removes the 128GB limitation in the future." Is this realistic?

It is a very bad idea. Unlike normal iMac Xeon in iMac Pro has a quad-channel memory interface. That's one of the biggest advantages compared to i7/i9 CPUs. Not sure if it can operate with only two modules installed. In case it would run it is definitely sub-optimal as it is quite easy to see memory contention on many professional workloads even in quad-channel configuration.

 

[killermike2178]

Apple uses binned Xeon W CPUs, which have slightly lower clockspeeds than their non-binned equivalents. Perhaps besides having slightly lower clockspeeds, the binned CPUs might have a stricter limit of 128 GB supported memory, whereas the non-binned ones have a limit of 512 GB. Check out this Geekbench result:

https://browser.geekbench.com/v4/cpu/8211065

Notice that this user's iMac Pro has a non-binned version of the 10-core Xeon W processor (W-2155) inside of it instead of a binned 10-core Xeon W reserved specifically for the iMac Pro (W-2150B). Also notice that it has 262144 MB (256 GB) of memory inside as well. Unless this is just a Hackintosh made to think it's an iMac Pro, perhaps putting in a non-binned Xeon W will lift this imposed limitation of 128 GB of memory.

 

[redheeler]

Apple uses binned Xeon W CPUs, which have slightly lower clockspeeds than their non-binned equivalents. Perhaps besides having slightly lower clockspeeds, the binned CPUs might have a stricter limit of 128 GB supported memory, whereas the non-binned ones have a limit of 512 GB. Check out this Geekbench result:

https://browser.geekbench.com/v4/cpu/8211065

Notice that this user's iMac Pro has a non-binned version of the 10-core Xeon W processor (W-2155) inside of it instead of a binned 10-core Xeon W reserved specifically for the iMac Pro (W-2150B). Also notice that it has 262144 MB (256 GB) of memory inside as well. Unless this is just a Hackintosh made to think it's an iMac Pro, perhaps putting in a non-binned Xeon W will lift this imposed limitation of 128 GB of memory.

The genuine iMac Pro results have this identifier under Motherboard:

Apple Inc. Mac-7BA5B2D9E42DDD94 iMacPro1,1

Any iMac Pro result with a Core i-series processor is a Hackintosh. Those have this identifier under Motherboard:

Apple Inc. Mac-7BA5B2D9E42DDD94 1.0

So the result you posted looks to be a Hackintosh.

 

[294307]

512 GB of RAM. Jesus Christ, I was surprised enough when I first heard the company I used to work for started offering servers with 128 GB of RAM. My first question was: who needs this much memory?

Clearly enough people. I just need a moment to accept this...this... big number.



512 GB of memory. Bloody hell.

 

[alien3dx]

512 GB of RAM. Jesus Christ, I was surprised enough when I first heard the company I used to work for started offering servers with 128 GB of RAM. My first question was: who needs this much memory?

Clearly enough people. I just need a moment to accept this...this... big number.



512 GB of memory. Bloody hell.

We implement system with 128 GB RAM itanium server. Would said pretty odd even for a billing system. A good system only need max 16 GB ram.But today app, play with all the cache. Cache are quick but you retain old data which pretty bad. The only best way to utilize ram is ramdisk but hardly any application can put their cache file path ,if existed it very usefull. But nowdays , even ssd is fast enough so what the point of it.Unknown.