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Additional memory issue on 2019 iMac 27"

Crwmlw

Crwmlw

macrumors regular
Original poster
Jun 18, 2011
158
29
Chicago,Il
Hey all. I have a 2019 iMac 27" that came with 8GB of memory, I wanted to upgrade to 32GB so I purchased timetic brand off amazon and replaced the apple memory with the timetic brand in its original slots, since then the computer takes forever to start up, use programs etc. I took the timetec brand out and put the original apple memory in and everything is good. Obviously an issue with the memory. Any ideas on what to do? Different brand maybe? Thanks
 
I did return it to Amazon, thanks for the link, would it make a difference if I get 2 16GB or 4 8GB?
 
Are you sure you inserted the new RAM in the same slots? I don't know about this particular iMac, but sometimes the slotting is not adjacent. In other words, for fastest RAM response, you need to match the original and/or insert new RAM in the other 2 slots that are free. This video may help if you don't recall where the originals were inserted...


Are you sure you matched the RAM details (speed, type, etc) EXACTLY? Not just any old RAM will do, even if it perfectly fits into the slots. I hopped onto Other World and it appears the 2019 27" uses 2666MHz DDR4 PC4-21300 RAM. Apple's own website says 21333 (I didn't dig in further but this might be a difference between Core I5 vs. Core I7 CPUs but that's just a wild guess) and adds unbuffered and nonparty. Is that what you bought or were 1 or more of those details different?

The key to success here is getting perfect replacement RAM (details) and inserting in the exact same slots OR getting 4 sticks of perfect replacement RAM (details) and filling all 4 slots.

With a goal of 32GB total, the difference in 2 sticks vs. 4 is the ability to further expand RAM later. For example, you could jump to 32GB now in 2 sticks and- if you discover you need more- you still have 2 RAM slots open for more. Also, if the original 8GB is in 2 slots, you could just leave it, add 2 sticks for 32GB more and enjoy a total of 40GB RAM for now. Again, key here is to know which slots are bank A vs. bank B. So you need to dig in and be sure mixed RAM is in the right slots. That may be adjacent slots (like 1 & 2 as A and 3 & 4 as B) or it might be odds (1 & 3) and evens (2 & 4). Do the research if you don't know and be sure to know which is right for that iMac.
 
Last edited:
HobeSoundDarryl said:
Are you sure you inserted the new RAM in the same slots? I don't know about this particular iMac, but sometimes the slotting is not adjacent. In other words, for fastest RAM response, you need to match the original and/or insert new RAM in the other 2 slots that are free. This video may help if you don't recall where the originals were inserted...


Are you sure you matched the RAM details (speed, type, etc) EXACTLY? Not just any old RAM will do, even if it perfectly fits into the slots. I hopped onto Other World and it appears the 2019 27" uses 2666MHz DDR4 PC4-21300 RAM. Apple's own website says 21333 (I didn't dig in further but this might be a difference between Core I5 vs. Core I7 CPUs but that's just a wild guess) and adds unbuffered and nonparty. Is that what you bought or were 1 or more of those details different?

The key to success here is getting perfect replacement RAM (details) and inserting in the exact same slots OR getting 4 sticks of perfect replacement RAM (details) and filling all 4 slots.

With a goal of 32GB total, the difference in 2 sticks vs. 4 is the ability to further expand RAM later. For example, you could jump to 32GB now in 2 sticks and- if you discover you need more- you still have 2 RAM slots open for more. Also, if the original 8GB is in 2 slots, you could just leave it, add 2 sticks for 32GB more and enjoy a total of 40GB RAM for now. Again, key here is to know which slots are bank A vs. bank B. So you need to dig in and be sure mixed RAM is in the right slots. That may be adjacent slots (like 1 & 2 as A and 3 & 4 as B) or it might be odds (1 & 3) and evens (2 & 4). Do the research if you don't know and be sure to know which is right for that iMac.
Click to expand...
 
The memory had the same exact specs and the ram was put into the same slots as the original Apple ram, slots 2 and 4. Maybe the quality of the ram?
 
Crwmlw said:
The memory had the same exact specs and the ram was put into the same slots as the original Apple ram, slots 2 and 4. Maybe the quality of the ram?
Click to expand...
 

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I opened that specific set in Amazon then searched reviews for iMac 2019 and most say it works fine with iMac 2019 27" but a few says it didn't. I didn't count them all but it looks like the split is about 70:30 on works/doesn't work. My guess is quality control problems.

This RAM is priced at $40. The OWC variation is priced at $60. You might want to pay the extra $20. OWC RAM usually works great in Intel Macs.
 
Thank you, I was reading on OWC’s website and kinda the same reviews, like 70:30. So I’m unsure if I should still try it. Thanks a lot doing what you did.
 
The RAM brand with the "best" reputation is Crucial (aka Micron).
I have used both Timetec and Crucial memory in iMacs with no problem.
Although OWC generally has a good reputation for RAM, there have been reports of kernel panics when using OWC RAM in certain configurations, so they are not perfect.

Note there are actually only about 3 manufacturers of the memory chips: Micron, Hynix, Samsung, and perhaps a few others. The DIMM manufacturers just assemble these into DIMMs.
Note that most of the RAM manufacturers have "Made for Mac" versions of their DIMMs, supposedly with more quality control. Whether these are actually any different from their regular DIMMs is debatable, aside from having a small price premium.
All RAM manufacturers have occasional failures. Suggest use one that has a lifetime warranty with free returns.
Amazon reviews and ratings are worthless.
 
Last edited:
wilberforce said:
The RAM brand with the "best" reputation is Crucial (aka Micron).
I have used both Timetec and Crucial memory in iMacs with no problem.
Note there are actually only about 3 manufacturers of the memory chips: Micron, Hynix, Samsung, perhaps one other. The DIMM manufacturers just assemble these into DIMMs.
Note that most of the RAM manufacturers have "Made for Mac" versions of their DIMMs, supposedly with more quality control. Whether these are actually any different from their regular DIMMs is debatable, aside from having a small price premium.
All RAM manufacturers have occasional failures. Suggest use one that has a lifetime warranty with free returns.
Amazon reviews and ratings are worthless.
Click to expand...
Thank you, I can’t seem to find the crucial brand for my model.
 
Have used OWC chips in a 2019 27" i9 since new. Zero problems.

The jungle place is the last place I'd buy memory from, and be thankful that whatever # the seller sent you didn't wreck your system. Buy only and directly from a reputable Mac memory specialist.
 
Sippincider said:
Have used OWC chips in a 2019 27" i9 since new. Zero problems.

The jungle place is the last place I'd buy memory from, and be thankful that whatever # the seller sent you didn't wreck your system. Buy only and directly from a reputable Mac memory specialist.
Click to expand...

There is no OWC chips in the first place. They just purchase/order RAM from other makers and relabel them with OWC brand. Tear-off the OWC label and you will see the real maker's name.
 
It is not unlikely that an old Firmware on the iMac is responsible for the 70:30 "luck" with Ram.
Apple Firmware Updates are delivered with MacOS so what Version is running on your iMac ?

eclecticlight.co

How to update your Mac’s firmware

iMac17,1 and other Mac models which don’t update their firmware properly can be brought fully up to date. What’s more, Apple Support is now reluctantly sorting this out those who persis…
eclecticlight.co eclecticlight.co
 
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