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A2116 / 2019 / 3.6 GHz quad-core i3, 3.0 GHz 6-core i5, or 3.2 GHz 6-core i7 processor. Released March 19, 2019.

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Why does the Ram speeds slowdown in 3.6GHz quad-core when upgrading?

PC4-21300 DDR4 2666MHz SO-DIMMs will operate at 2400MHz speeds in iMac19,2 models with a 3.6GHz Quad-Core i3 Processor.

I want to know why this happens and if there is a way around it? Or should I not worry about the 266MHz speed difference?

What difference do 2666MHz and 2400MHz have on Ram speed?

How much will it truly slow down if I upgrade from 16GB ram to 64GB ram, or will I even notice?

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Your DDR4 RAM options are: 8, 16, or 32 GB PC4-19200 (2400 MHz) when you have a Core i3 CPU or PC4-21300 (2666 MHz) when you have a Core i5/i7. It is also possible to go to 64GB with either of the Core i5/i7 CPU's. The limitation is the CPU's clocking.

As to speed I think you've got things backwards the higher end models have higher access speed RAM What are Memory Timings & How they Work: CAS, RAS and tRAS Explained

Unlike PC, Mac's timings are fixed based on the CPU ID held in the systems EFI.

The quantity of RAM does have a bearing! The deeper the reach the longer it takes! Independent of the RAM's clocking. Its advised not to max out the RAM if you don't need it! So make sure the applications and your data set can really use it beforehand. 32GB is a good size for an advanced amateur. The 21.5" system is not seen as a Pro level machine and do its graphics it is really a lightweight for what a Pro would need.

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I work from home using Microsoft office programs, and I use it for my hobby as well, usually at different times. Occasionally I may have excel, my one driver, Adobe illustrator, and design space open to make SVG and modify cut files. I constantly have to free up ram space because I’m maxing out, and I currently have 16GB ram.

I was hoping for a better solution than dropping 2000+ on a new Mac when I could upgrade mine.


Is there anything I can do to maximize what I already have? I see there are kits for storage along with kits for ram.


@fixitgirl1988 - What is your storage setup? I would focus on it as that's likely your performance pinch-point.

I would stick with 16GB of RAM given your usage and look at upgrading your storage.


I have the 1 TB Serial ATA (6Gb/s) hard drive built in storage and a LaCie 2TB external hard drive.


I would switch out the HDD for a SSD. That’s likely what’s holding you back. Sadly, a HDD only system doesn’t offer the second drive port (NVMe/PCIe).


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