What RAM to buy to update new iMac launched today?

[SaSaSushi]

I could benchmark my computer 10 times and get 10 different readings, you know that and I know that. Lower CL RAM does not automatically translate to faster speeds and DEFINITELY offers no noticeable performance advantages. Anybody who’s spending more money to get lower timings and expecting performance gains on iMac RAM is being duped.

At least you threw in noticeable performance this time. No one that I am aware of in this thread is paying more for lower CL RAM either so far as I know. One of the reasons I bought the Ballistix is because it was the most inexpensive option for me at the time. I think you're trying to stir up some sort of controversy that doesn't exist.

 

[froth]

Does anybody knows what is the right order for RAM which come in dual rank? I know that Apple ram is installed in 1st and 3rd slot. That suggest that pairs are 1,3 and 2,4. However when we look in slots in macOS it looks like:
SLOT 1 corresponds BANK 0/DIMM0
SLOT 2 corresponds BANK 0/DIMM1
SLOT 3 corresponds BANK 1/DIMM0
SLOT 4 corresponds BANK 1/DIMM1

so it means that memory which is in dual rank should be in same BANK ?

 

[SaSaSushi]

Does anybody knows what is the right order for RAM which come in dual rank? I know that Apple ram is installed in 1st and 3rd slot. That suggest that pairs are 1,3 and 2,4. However when we look in slots in macOS it looks like:
SLOT 1 corresponds BANK 0/DIMM0
SLOT 2 corresponds BANK 0/DIMM1
SLOT 3 corresponds BANK 1/DIMM0
SLOT 4 corresponds BANK 1/DIMM1

so it means that memory which is in dual rank should be in same BANK ?

Matching RAM should be in DIMM0 and DIMM1 (alternating slots) for dual channel, exactly as Apple ships it. See this thread for more information.

 

[Dead_serious]

Does anyone know if dual or single ranked ram makes a difference with the iMac 21.5"?

 

[SaSaSushi]

Does anyone know if dual or single ranked ram makes a difference with the iMac 21.5"?

Judging by earlier posts to this thread (see around page 10), it shouldn't make a difference as long as the RAM otherwise meets the specifications (260-pin PC4-19200). It seems that all modules of 16GB or larger are dual-ranked.

 

[83metoo]

Hello from Germany,

just ordered my iMac 27" with 8GB Ram - I want to change the Ram with 4 x 16GB Ram because I do some FCPX works for my youtube channel 83metoo.

- HyperX Impact, I red it can make some issues in fact of automatic overclocking
- Crucial says on there website the Ram is not compatible with the 2017 iMac

What is your reference Ram for 2017 iMac?

Thanks

 

[SaSaSushi]

- HyperX Impact, I red it can make some issues in fact of automatic overclocking

If you're not planning on using Hyper-X in combination with Apple's RAM, users in this thread have reported it works fine. It does not mix well with non-Hyper-X.

- Crucial says on there website the Ram is not compatible with the 2017 iMac

The Crucial Ballistix I've been using in my 2017 iMac with perfect performance for over 3 months now is noted to be incompatible with 2017 iMac in giant red letters on their website.

As long as it meets the timing specs, the lack of "for 2017 iMac" label shouldn't make any difference at all.

 

[83metoo]

If you're not planning on using Hyper-X in combination with Apple's RAM, users in this thread have reported it works fine. It does not mix well with non-Hyper-X.



The Crucial Ballistix I've been using in my 2017 iMac with perfect performance for over 3 months now is noted to be incompatible with 2017 iMac in giant red letters on their website.

As long as it meets the timing specs, the lack of "for 2017 iMac" label shouldn't make any difference at all.

Hi and thanks for fast reply.

What I also found out is that Kingston also have another Ram that is official compatible, KCP424SD8/16

https://www.kingston.com/de/memory/search?DeviceType=2&Mfr=APP&Line=iMac&Model=96522

Are there any experiences with that one?

 

[SaSaSushi]

What I also found out is that Kingston also have another Ram that is official compatible, KCP424SD8/16

https://www.kingston.com/de/memory/search?DeviceType=2&Mfr=APP&Line=iMac&Model=96522

Are there any experiences with that one?

Try the search tool. Using it I was able to quickly find this post.

 

[Clinbio]

Can I add just one , e.g a Crucial CT16G4SFD824A model, to the new 2017 model 27inch iMac? So it goes from 8 to 24 Gb? If that's possible, what slot occupation would be the best ? Currently the two 4Gb are at slot 1 and 3. Have the single 16 Gb module at slot 1 and move one 4Gb to slot 2 (and leaving the other at slot 3?)?
I don't want to fill up the last empty slot already but might do that some time in further future.

 

[SaSaSushi]

As mentioned, matching RAM should be in staggered slots, exactly as Apple ships it. I'd advise you to leave the Apple RAM as it is and install the 16GB DIMM into slot 2. It should run fine but you will always get better performance with dual channel.

As long as there is a slot between the matching DIMMs you're doing it right.

 

[Zapp21]

Can I add just one , e.g a Crucial CT16G4SFD824A model, to the new 2017 model 27inch iMac? So it goes from 8 to 24 Gb? If that's possible, what slot occupation would be the best ? Currently the two 4Gb are at slot 1 and 3. Have the single 16 Gb module at slot 1 and move one 4Gb to slot 2 (and leaving the other at slot 3?)?
I don't want to fill up the last empty slot already but might do that some time in further future.

Thought I made a good deal on 16GB Crucial Kit to upgrade my 8GB RAM 5K iMac. As it turns out, I ordered a single module, no kit.

Do you already have some experience with that 4-16-4 combo? I don't know whether I should keep mine. I could send it back and order two 8GB sticks instead. They are more expensive though.

 

[SaSaSushi]

Do you already have some experience with that 4-16-4 combo? I don't know whether I should keep mine. I could send it back and order two 8GB sticks instead. They are more expensive though.

I see no reason why it shouldn't work, albeit not in dual channel mode.

 

[LGIR627]

So I've spent 3-4 hours reading this thread and researching and cannot seem to figure out what RAM to order. I have a base model 2017 27" on order. I am keeping the 8GB of Apple RAM and want to add a 16GB (8GB x 2) kit for a total of 24GB. I just want to be able to drop it in and everything works. It seems that every brand (Crucial, OWC, Corsair, etc.) has reviews/comments of people having issues.

Can anyone who was in a similar situation let me know which brand RAM they purchased?

It seems like when I upgraded the RAM of my 2015 iMac, it wasn't so complicated and didn't require as much thought.

 

[SaSaSushi]

I just want to be able to drop it in and everything works. It seems that every brand (Crucial, OWC, Corsair, etc.) has reviews/comments of people having issues.

Strange, I don't recall anyone posting about having issues with Crucial.

So long as it is 260-pin PC4-19200 you should be fine, whether it is labeled as "for iMac" or not.

 

[Huginnmuninn]

They all (probably) work about as well - Crucial, Kingston, Ramjet, OWC, whomever - and they all have lifetime warranties if there's a problem.

Some people have problems, some don't, some need to re-seat in different slots and restart, some don't.

Crucial is owned by Micron Technology, a $20 Billion/year corporation which makes its RAM (and sells to manufacturers, to consumers, and to resellers), while companies like OWC buy theirs from manufacturers and resell it. For what it's worth, for my last RAM upgrade, for a Mac mini, I bought direct from Crucial and had no problems.

 

[colodane]

I've purchased from Crucial for both my 2011 and 2017 iMacs. No issues either time.

 

[J.Gallardo]

Thank you, SaSaSushi, for all the info you've spread all along this thread.
I installed two Ballistix 16Gb modules because of price. All is working perfectly well (even High Sierra!) on my new 27"-i5-580 for a month now.
32Gb costed 242€, which is a nice price, now that has become more expensive in general.
Amazon asks for 370€ now for same size Crucial modules. They are the "official" Apple compatible ones (part n.CT2C16G4S24AM), because they don't use a very specific material on it (or involved in its making), which is banned by Apple's environment protection policy.
I think every named brands should work if they fulfill technical specs requirements.

 

[bunnysnacks]

i got the owc 64gb memory upgrade kit for mine, works good

 

[Cordorb]

and once again to KNOW it "works good" run the built in Apple test

http://www.macissues.com/2014/03/21/how-to-run-and-interpret-apples-hardware-tests-on-your-mac/

(hold down the D key on boot)

do the short test first to see how the testing goes - then a long version

 

[SaSaSushi]

I installed two Ballistix 16Gb modules because of price. All is working perfectly well (even High Sierra!) on my new 27"-i5-580 for a month now.

I'm really glad to hear that! My Ballistix is going on seven months now with no issues whatsoever.

The Ballistix (and other RAM) has also raised in price considerably for me as well since I bought it back in June.

and once again to KNOW it "works good" run the built in Apple test

I've seen a lot of cases where Apple's own hardware test will green light bad RAM. A much better way to vet bad RAM is to get a copy of Memtest86 and let it run for a few hours. If you make it through three or four complete passes without errors you're good to go.

 

[whcvip]

I'm really glad to hear that! My Ballistix is going on seven months now with no issues whatsoever.

The Ballistix (and other RAM) has also raised in price considerably for me as well since I bought it back in June.



I've seen a lot of cases where Apple's own hardware test will green light bad RAM. A much better way to vet bad RAM is to get a copy of Memtest86 and let it run for a few hours. If you make it through three or four complete passes without errors you're good to go.

+1 for Ballistix, have 64GB in my 2017 iMac, and have been running perfect. Did the Memtest86 for several hours and no error at alt, and several month using the machine have been 100% stable. Not yet maxed out the 64GB and run video editor, photo editor, safari, chrome and other apps at the same time right now only uses 17.5GB

 

[haruhiko]

I just bought two 8GB Kingston HyperX DDR4 SODIMM 2400MHz for my iMac 5K 2017. I nearly panicked when the iMac wouldn't turn on after the installation. I confirmed that every RAM is firmly in place. It still wouldn't turn on.

Finally, I rearranged the RAMs to switch the positions between the stock RAMs and the new RAMs, then the iMac finally turned on.

Everything is running fine now.

 

[haruhiko]

I just bought two 8GB Kingston HyperX DDR4 SODIMM 2400MHz for my iMac 5K 2017. I nearly panicked when the iMac wouldn't turn on after the installation. I confirmed that every RAM is firmly in place. It still wouldn't turn on.

Finally, I rearranged the RAMs to switch the positions between the stock RAMs and the new RAMs, then the iMac finally turned on.

Everything is running fine now.

I just found out the new RAM isn't really compatible with the one pre-installed on my iMac.
Now the RAM speed is reduced to 2133MHz.

Avoid the Kingston HyperX.
[doublepost=1516361207][/doublepost]

The problem being (as I think you were the one who pointed out) that some RAM a la HyperX can't maintain its rated speed at the higher latency, which in turns drags the speed of the Apple RAM down to its level if it falls back to 2133Mhz.

If the DIMM is rated at 2400Mhz at CL17 all is well. 2400Mhz at anything lower can be a bit of a crapshoot if you're mixing with stock, though you're right on that I wouldn't normally concern myself with CL16 vs. CL17. I'd watch out heavily for "enthusiast" RAM with low CLs though.

Thanks.. this explains why my stock RAM + HyperX can only run at 2133MHz...
$200 lesson well paid.

 

[Chancha]

The stock RAM is 2400MHz with CL17, if the intension is to keep 2 stock and add 2 yourself then it is best to match exactly those two specs to avoid compatibility issues.
The overclocked / lesser latency variants can be used, but only ideal if you put just the 2/4 of them in the iMac, taking out the stock.