CT2K16G4S266M 32GB (16GB x2) Mac Memory Kit (DDR4, 2666 MT/s, PC4-21300, CL19, Dual Rank x8, SODIMM, 260-Pins)

I purchased memory from OWC for my 2020 iMac 27" twice, and each time the memory did not work. One set wouldn't allow my computer to turn on at all, and the next set caused my computer to reboot about 5 mins over and over. I was very frustrated, and decided to give the Crucial memory before giving up on upgrading. It installed in ~3 mins and has worked flawlessly with no reboots, no crashes, no issues at all. The iMac has never run better, and I'm relieved to have found a solid solution for a good price.

I was a bit concerned prior to installing my 32 GB kit - the reviews I read here, made it seem like I would encounter issues with slot placement and seating the cards. I'm a mom of two and I'm moderately tech-savvy (I've installed an SSD drive in my previous iMac without issue), but I'm in no way an Apple Genius. The entire process actually took me about 15 minutes (to be honest, 10 minutes of that was just unplugging everything and setting-up a clear/soft workspace on which to set the computer). After popping the cover off the back of the machine, I didn't change the position of the original RAM cards- I just added the two new 16 GB cards to the remaining/available slots- I didn't have a problem seating the cards at all. Then I replaced the cover, plugs and powered my machine on- there was an initialization prior to my log-in screen that was a tad bit longer than usual, but once I signed in, everything seemed in order- "About this Mac" reflected that I had 40 GB of RAM and the application I use to monitor my RAM usage had shown an impressive increase. Prior to installing this RAM- my available RAM would hover around a paltry 25 MB (I use Adobe applications, like Photoshop, Lightroom, Illustrator and InDesign regularly), but after installing the upgraded RAM- I'm showing at least 30 GB of available RAM. For the price and ease of installation- I can't give a better endorsement. If you're on the fence about buying it, I can honestly say I'm extremely happy with this product!

9-4-25. I've had these for only a couple of days and have no problems. My Photoshop and Lightroom Classic programs have gotten so big that they were crashing my 2020 imac. The 8 gigs it came with couldn't handle the programs anymore. I installed these 2-16 gig cards along with the 2-4 gig cards that came with the system. I left the original 4 gig cards in slots 1 and 3 and put these in 2 and 4 as recommended by the interweb. The machine fired right up and I've had no issues so far with the programs. From 8 gigs to 40. If anything goes sideways I'll update this review.

As always, Crucial is the best all around brand for Apple's (upgradable) computers. Crucial is owned by Micron, a company that Apple themselves uses as an OEM supplier. If you've ever pulled RAM out of a Mac before, you might have seen "Micron" on the labels. Crucial supplies their own branded components that you'd never see inside as OEM on a Mac, but the RAM itself is Micron underneath the Crucial label. It's the brand I always trust most with RAM upgrades on a Mac. It's not the cheapest, and is far from the most expensive. But it is the most dependable. And trust me, you want dependability if you're going to go through the hassle of upgrading the memory on a 2019 iMac. That said, installing RAM on a 2019 21.5" iMac is no easy task, at least not for the faint of heart. You'll also need to order yourself new display adhesive as you cannot reuse what was on the machine. I'd also advise that if you're going to go in, to also upgrade anything else that needs upgrading (SSD, adding a second drive, CPU, etc). Because it's not easy or fun in there, it's just nice to knock it all out of the park if you can. Also make sure you have your Torx screwdrivers ready as you'll need T5, T6, T8, T9 and T10 sizes, in addition to a P00/P000 screwdriver. Make sure the screwdrivers come magnetized, and if not get yourself a driver magnetizer/demagnetizer. It's quite the journey in there, which you should look into over at ifixit.com before you order a single thing.

Perfectly fit into my Mac. Authentic products.

It worked perfectly for some time and stopped working eventually, not satisfied with the product

Werkt perfect in een Synology DS220+.

Para todos aquellos que no lo saben y quieren cambiar o incrementar la memoria de su iMac, Macbook Pro, etc. Les recomiendo ampliamente este modelo y sobretodo esta marca. Puede que no sea muy conocida en México pero en el gabacho es ampliamente usada. Solo basta revisar los reviews de Amazon USA para darse cuenta. La Marca Crucial no es la más barata pero si es de las mejores especializadas en Mac. En el caso de las iMac fíjate si la tuya tiene una tapita en la parte de atrás, justo arriba de donde se conecta el cable. Es muy facil añadir o intercambiar los dimms. Solo tienes que tener cuidado de escoger el dimm que es compatible con tu computadora. En este caso estos dimms son perfectamente compatibles con las iMacs 5k de 27" 2017 y 2018. Hay que tener mucho cuidado al escoger memoria RAM para Mac. Aunque puede parecer que muchos modelos le quedan, no es así. La más pequeña variación y tu memoria será inutilizable. Este modelo cumple exáctamente lo que Apple pide y además el fabricante lo está menconando en la descripción. Aparte estas son dual channel, lo que te permite tener dimms diferentes por sector. Por ejemplo uno de 16gb y otro de 4gb (el que viene en la mac) y así tendrás 20 ó 40. Te la recomiendo mucho si quieres ahorrar mucho dinero. Instalarla en una iMac es muy pero muy sencillo. En una MacBook Pro también es sencillo siempre que no venga soldada a la placa base. Esta es una compra casi mandatoria para todo aquel que invierte en una computadora de estas características. Inclusive si añades 8 gb extras a la iMac de entrada el cambio en desempeño es impresionante. Lo mínimo que debería de traer una computadora así son 16Gb. Pero todas traen 8. Espero que te haya servido mi mini reseña.

ネットで調べてこれが良さそうと思い購入 64GB(32GB×2)を既存の8GB(4GB×2)と入れ替えて取り付け、正常に作動 耐久性は不明 11月8日注文20日海外発送で到着