2020 iMac RAM Upgrade

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Level 1

16 points

2020 iMac RAM Upgrade

Hello.

I want to fill the two remaining empty RAM slots with 32Gb (2x 16Gb) of memory. I know its DDR4 260-Pin SODIMM 2666 (PC4-21300) Unbuffered and non-parity, but theres normal RAM, Single Rank and Dual Rank.

So whats the difference and what do i need?

Also is it better to get these in pairs rather than a single chip? currently theres 2x 4Gb chips installed. Apple says: minimize the capacity difference between Channel A (slots 1 and 2) and Channel B (slots 3 and 4) when possible.

Many thanks.

iMac Line (2012 and Later)

Posted on Oct 7, 2020 10:29 AM

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Answer 1

Best reply

Wobble Woo Author

Level 1

16 points

Oct 12, 2020 3:46 AM in response to rkaufmann87

If anyone is reading this, Apple preinstalls two 4Gb RAM in slots 1 and 3 (to make use of dual channels im guessing) however if you replace these with two new larger chips the memory speed drops to 2133, as rkaufmann87 points out.

Similar chips need to be paired in 1&2 and 3&4

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Answer 2

rkaufmann87

Level 10

140,700 points

Oct 7, 2020 10:56 AM in response to Wobble Woo

For iMacs ALWAYS in stall in mixed pairs, so 2 x 16GB is correct.

Below are screen shots to show the correct method of installing to get the fastest speed. Please pay close attention to the slots the RAM is installed in!!!

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Answer 3

rkaufmann87

Level 10

140,700 points

Oct 7, 2020 10:35 AM in response to Wobble Woo

When buying RAM for iMacs it is EXTREMELY important that you buy very high quality RAM. For that reason experienced users on these forums only recommend using OWC (www.macsales.com) or Crucial.com RAM. DO NOT buy from any reseller including Ebay, Amazon, Newegg etc.. only these two vendors. Why, simple because they sell high quality products at reasonable prices, offer excellent service, have lifetime warranties on RAM so there is no reason to second guess them.

If you plan on keeping the origianl RAM (smart idea) installed, please move them to slot 1 & 2 (these are the top slots) and add the new RAM to slots 3 & 4 and then you will get the best performance. I did this with my 2020 iMac and it's work great and I get the full 2666 MHz speed.

If you want proof of the performance, please let me know and I'll include a screen shot.

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Answer 4

Wobble Woo Author

Level 1

16 points

Oct 7, 2020 10:50 AM in response to rkaufmann87

I was planning on Crucial memory but thankyou.

But do i buy in pairs (2x 16Gb) or a single 32Gb chip?

And whats the difference between the single and dual rank chips?

Single Rank (£101.99):

Crucial CT2K16G4SFRA266 32 GB Kit (16 GB x2) (DDR4, 2666 MT/s, PC4-21300, SODIMM, 260-Pin) Memory

Dual Rank (£106.79):

Crucial CT2K16G4SFD8266 32 GB Kit (16 GB x 2) (DDR4, 2666 MT/s, PC4-21300, Dual Rank x 8, SODIMM, 260-Pin) Memory

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Answer 5

rkaufmann87

Level 10

140,700 points

Oct 18, 2020 2:58 PM in response to lavonne216

I bought OWC RAM, this is exactly what I bought. https://eshop.macsales.com/item/OWC/2666DDR4S32P/ and I already illustrated in an earlier post on this thread how they are installed and the speed results. If you live in an area (outside the USA) where OWC RAM is expensive, then please ONLY buy Crucial.com RAM. DO NOT BUY ANY OTHER BRANDS or from places like Amazon, NewEgg, etc...

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Answer 6

Wobble Woo Author

Level 1

16 points

Oct 19, 2020 3:34 AM in response to lavonne216

I added 32Gb 2x16 to my 2020 iMac and it's made a massive difference. I too had a 2011 iMac it was a real workhorse.

I got this:

Crucial CT2K16G4SFD8266 32 GB Kit (16 GB x 2) (DDR4, 2666 MT/s, PC4-21300, Dual Rank x 8, SODIMM, 260-Pin) Memory

Paid £106

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Answer 7

Oct 18, 2020 12:03 PM in response to Wobble Woo

what memory did you order? I was thinking I want t ad 2 32GB ... I do photoshop and digital art? got the new 2020 but it is not much better than my 2011 with 16GB installed...

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