OWC 128GB (4 x 32GB) PC21300 DDR4 2666MHz 260pin SO-DIMMs Memory Ram Upgrade Compatible with 27 iMac w/Retina 5K (Early 2019 and up) and Compatible PCs (OWC2666DR4S128S)
Condition: New
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FREE 30-day refund/replacement
To qualify for a full refund, items must be returned in their original, unused condition. If an item is returned in a used, damaged, or materially different state, you may be granted a partial refund.
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Availability:
In Stock.
Arrives
Friday, May 22
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Size: 128 GB (4 x 32 GB)
Color: 128 GB
Features
- OWC 256.0GB UPGRADE: Consists of Four 32GB DDR4 2666MHz PC4-21300 CL19 SO-DIMMs 1.2V 260-pin Memory Module Fully compliant with JEDEC specifications, ROHS compliant, warranty safe upgrade; Backed by OWC Memory Lifetime Limited Warranty including the OWC Lifetime Advanced Replacement Program
- COMPATIBLE WITH: 2020 iMac: iMac w/Retina 5K display (27 inch mid 2020) Model ID: iMac20,1 and iMac20,2 (3.1GHz i5, 3.3GHz i5, 3.8GHz i7, 3.6GHz i9)
- COMPATIBLE WITH: 2019 iMac: iMac w/Retina 5K display (27-inch Early 2019) Model ID: iMac19,1 (3.0GHz i5, 3.1GHz i5, 3.7GHz i5, 3.6GHz i9) Models: MRQY2LL/A, MRR02LL/A, MRR12LL/A
- PC COMPATIBLE WITH: works with compatible gaming laptops and PC desktops: Dell, HP , Toshiba, ASUS, Acer, Supermicro, Fujitsu, Gigabyte, Intel, Lenovo, LG, Samsung, Sony, Supermicro
- COMPATIBLE PART NUMBERS: CT2K32G4S266M, CT32G4S266M, KCP426SD8/32, CT32G4SFD8266, HMAA4GS6AJR8N-VK, M471A4G43MB1CTD, MUQQ2G/A
- INDUSTRY LEADING: Consumer Friendly Advanced Replacement Program and Limited Lifetime Warranty, which Includes Free Tech Support by Other World Computing
Brand: OWC
Computer Memory Size: 128 GB
RAM Memory Technology: DDR4
Memory Speed: 1333 MHz
Compatible Devices: Desktop
RAM: 128 GB DDR4
Brand: OWC
Series: OWC2666DR4S128S
Item model number: 2666DR4S128S
Item Weight: 2.08 ounces
Product Dimensions: 6.26 x 4.25 x 0.28 inches
Item Dimensions LxWxH: 6.26 x 4.25 x 0.28 inches
Color: 128 GB
Computer Memory Type: DDR4 SDRAM
Voltage: 1.2 Volts
Manufacturer: Other World Computing
Date First Available: April 3, 2019
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Friday, May 22
Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
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- PayTomorrow Financing
- Financing through Apple Pay
Learn more about financing & leasing here.
Top Amazon Reviews
Size: 32gb
Color: 4 x 8GB
Imac 2019 5k here. 8 Gb out of factory from 2x4 ram sticks. I tend to have a lot of things opened at the same time, but nothing out of the ordinary, a few chrome tabs, a few safari windows , WhatsApp, mail... It was ok with 8Gb but not lighting speed. I was getting the color wheel when trying to open a new tab sometimes. I Wasn't sure how much ram to get from Amazon but the cheapest approach was to do 4x8 since I dont do video editing or anything crazy, I didn't thing anything over 32 would be useful. Install: So they tell you to lay the Mac flat, which I didn't do. I installed the new ram with the iMac vertical: I removed the old old and put the 4 new ones in place I closed the memory compartment and the Mac wouldn't boot a few times I thought I installed them correctly but YOU HAVE TO MAKE SURE EACH IS FULLY, FULLY, FULLY in. A slight off position and your computer won't boot. After trial #3, the Mac booted no problem. Back to were I left when I turned it off prior to ram upgrade. I am now using about 10gb of Ram out of the 32 available but the Mac monitor, with the same apps opened as prior. The difference is night and day when I do something, wether it is a webpage or opening iPhotos or pages, it is just instant. At $150 , it is overall a cheap upgrade given how much money we put in our machines. Super happy with the purchase given the amount of time I spend on the computer, I appreciate the smoothness.
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Reviewed in the United States on July 11, 2020 by Nicolas. g Nicolas. g
Size: 64 GB (2 x 32 GB)
Color: 2 x 32GB
Works and fits great in my HP EliteBook 840 G7. The RAM was well packaged and easy to install. I upgraded to the 64GB (2 x 32GB), and my laptop recognized the full capacity right away. The speed matches the specs exactly as listed. No issues so far.
Reviewed in the United States on July 29, 2025 by Anna
Size: 64 GB (2 x 32 GB)
Color: 2 x 32GB
My 2019 Retina 5K 27" iMac came with 16gb factory installed - two 8gb cards. I bought these two 32gb cards to upgrade memory. Nothing could be easier - open the memory compartment in the back and install the two new cards. The factory cards were in slots 1 & 3 (or 0 & 2 if you want to use the odd Apple numbering). I left them in place despite Apple spec that 64gb was max for this iMac. Put the two new 32gb cards in the open slots 2 & 4 (1 and 3 for Apple purists) - closed up and restarted the iMac. It took 30 seconds or so to orient to and recognize the new memory, then booted up fine... no problems or issues and I now have 80gb of fully recognized and usable RAM in my computer. The OWC cards are cost effective, easy to install (press them down into the open slots) and work like a charm.
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Reviewed in the United States on March 6, 2022 by Urey W. Patrick
Size: 32gb
Color: 2 x 16GB
Instead of paying ludicrous prices for installed memory on my MacMini, I read a story in 9to5Mac about upgrading memory yourself. Armed with a YouTube video, a MacMini tool kit, and these memory sticks, I tore apart my 2018 MacMini and had it back together within 30 minutes. I took out the 2 x 4GB RAM sticks in it, and replaced it with these. Upon booting, no issues encountered. Follow installation steps exactly as in the video and make sure the memory sticks are firmly installed and reseated in the motherboard as shown. Also ensure you are careful unlocking and reseating all power cables, speaker cable and placing screws back in the reverse order you removed them during reassembly. It's not hard at all. Get the tool kit, which you will find online for less than 20 bucks, and save hundreds over Apple pre-installed prices. Also, you cannot upgrade some Mac Minis that have model years that have permanently installed RAM into the motherboard. The 2018 model is ok. 2012, which my wife has, cannot be upgraded. Check your model number and the OWC website if you are unsure as to what you have. No issues in operation since installed, this is a wise investment. OWC has quality products and this is a classic example.
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Reviewed in the United States on November 18, 2020 by Rick Lowe
Size: 128 GB (4 x 32 GB)
Color: 128 GB
I was looking either a new computer or an upgrade, so I choose the latter. My iMac 27" has 8 GB original apple memory RAM, which was just enough for simple daily use. However, once I started to working again my computer had hard time to handle all those graphic softwares, top of the heavier system after the updates. After this upgrade from 8GB to 128GB, now my computer works amazingly fast. It's very easy to install, once it's placed in correctly, the computer takes care of it by itself. However, it needs some time to recognize the installation, so I had to retry few times. I think I was a bit impatient. It's compatible with my iMac27, cost effective and improvement on performance saves so much of my time. I'm very happy with this product.
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Reviewed in the United States on July 27, 2025 by Loria
Size: 32gb
Color: 2 x 16GB
The two 16gb of RAM showed up yesterday, and I was very excited to install them into my computer. However when I opened the envelope they were shipped in I was a little disappointed to see that the nearly $200 worth of RAM came in a zip lock bag. They installed fine and seem to be working well, I just wish there was a little more pride in the affordable RAM in regards to how they're packaged and delivered.
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Reviewed in the United States on August 14, 2019 by Jon
Size: 16gb
Color: 2 x 8GB
Mu purchase of 16 GB (2x8 GB sticks) of DDR 4 2666 ghz ram went smooth all of the way. It was delivered on time and very easy to install in my 2020 iMac 27". I figured I only needed 16 GB based on my Apple computer Activity Monitor assessment but decided I would try to add it to the existing 2x4 GB sticks I had. For the un-initiated: This computer uses 2 channels for ram. These both must be used or the effect will be decreased random access memory **availability**. There are 4 (four) slots for ram sticks. Channel A is slot 1 and 2, Channel B is slots 3 and 4. To work optimally, so I was led to understand by YouTube videos, the must carry the same amount. To illustrate, I now have 8 + 4 in Channel A and 8 + 4 in Channel B. If I had put this in any other configuration it would not work the same nor would it be optimal. In summary, I now have more than enough ram (there was no availability of 8 GB (2 x4 sticks). It was a bit more expensive than I had seen a year ago but that is life, I guess, you snooze you lose :^)
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Reviewed in the United States on October 21, 2022 by Peter A. White