PC4-21333 vs PC4-21300 RAM

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lordmag Author

Level 1

13 points

PC4-21333 vs PC4-21300 RAM

Apple support for adding extra RAM to 2019 iMac 27 5k retina specifies to add modules with these specs:

Use Small Outline Dual Inline Memory Modules (SO-DIMM) that meet all of these criteria:

PC4-21333
Unbuffered
Nonparity
260-pin
2666MHz DDR4 SDRAM

Online though (Apple store oddly doesn't sell RAM modules for iMacs...) I only found PC4-21300.

Are they ok or would they turn out to create problems?

I have a 2019 iMac 27 5k retina with two RAM slots used by 2 8GB modules and would like to buy 2 more to fill the remaining two slots

iMac 27″, macOS 10.15

Posted on May 30, 2020 3:14 AM

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Answer 1

Best reply

dialabrain

Level 10

122,483 points

May 30, 2020 3:32 AM in response to lordmag

They are one and the same.

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Answer 2

K Shaffer

Level 7

34,966 points

May 30, 2020 3:37 AM in response to lordmag

Providing you can identify the build model year details specifically,

this should be easily found at least online. Then use info anywhere

that has correct matching specifications. OWC has exacting specs &

guarantees specified RAM modules will work; just get correct ones.

The iMac 27-inch model had two 2019 models; one batch, 4K.

And another one shows 5K. So there are other identifiers, too,

In a generalized fashion, an Upgrades for Mac (OWC) shows

both. [This page address has upgrades/imac19-1 for 27-in. 5K]

Your model 27-inch 5K iMac (2019) can use up to 128GB (4 pcs)

according details shown here: [128GB Memory Upgrade]

Examples each: All RAM Memory Upgrades, this Mac, here.

Good luck & happy computing!🌻☘

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Answer 3

lordmag Author

Level 1

13 points

May 30, 2020 3:27 AM in response to SeaPapp

crucial doesn't have PC-21333, only PC-21300. That's where I was trying to buy and that's why I asked the question

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Answer 4

SeaPapp

Level 7

26,486 points

May 30, 2020 3:26 AM in response to lordmag

Macs require exact spec ram, failure to do so will result in problems. Only buy quality ram from either OWC https://eshop.macsales.com/ or Crucial https://www.crucial.com/

Avoid other bargain basement brands.

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Answer 5

dialabrain

Level 10

122,483 points

May 30, 2020 3:27 AM in response to lordmag

Both OWC and Crucial sell compatible PC4-21300 RAM modules.

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PC4-21333 vs PC4-21300 RAM

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