What RAM to buy to update new iMac launched today?

[3drteest]

Has anyone gotten the Crucial CT2K16G4SFD824A memory to work?

 

[Trebuin]

I would love to see if there really is a difference in the same speed, but lower latency between the kingston & the crucial memory (or the apple given that it's the same clock as crucial)

 

[Echophage]

Did have any idea how to measure the ram speed? Additional to the Kingston hyperx cl14 I have 64GB crucial ballistix here with cl16 that I be able to test. And on Saturday will arrive crucial ballistix 2*32GB kit ddr4-2666, that I also will test.

Again, anybody know how to speed test the ram?

 

[Glideslope]

Well I can tell you the standard 2 x 4GB modules in my iMac are Micron (Crucial).

I just tried installing my 2 x 8GB Crucial modules purchased directly from their web site (guaranteed to be compatible) but I can't get my iMac to start with them installed. Either by themselves or in addition to the stock modules. I only get a blank screen which doesn't even get to the Apple logo. No beeps or anything.

By the way, this is my first Mac to also not have the start-up chime. It's times like this I wish it was still around to help me know what's going on.

Has anyone else had trouble with their newly purchased Crucial RAM?

I've never had an issue with Crucial since my first purchase with them in 2008. They are Micron which is what Apple is putting in the 2017 iMac, hence the shortage on their website until late July. However, nothing is impossible. As long as they are correct DIMM's Crucial will replace them for no charge.
[doublepost=1497452997][/doublepost]

Is it smarter to buy 4x8 or 2x16? I see people here buying 4x but i'd rather buy 2x16 if that is possible (so i can expand later) or is this no option?

I would go with 2X16.

 

[yadmonkey]

I've never had an issue with Crucial since my first purchase with them in 2008.

Once I had an issue with their modules - I think it was the 12" Powerbook G4, which wouldn't boot with the recommended Crucial RAM. They replaced the modules and the same problem persisted on two identical Powerbooks. Then I went with OWC and it worked fine.

In Crucial's defense, the G4 Powerbooks in general were the pickiest machines I can remember when it came to RAM. I've opened hundreds of Apple laptops and Micron is probably the vendor I've seen most for Apple's factory configs - I have to go back to 2005 to dredge up the one issue I had. I've used Crucial many times since without issue.

 

[Glideslope]

Once I had an issue with their modules - I think it was the 12" Powerbook G4, which wouldn't boot with the recommended Crucial RAM. They replaced the modules and the same problem persisted on two identical Powerbooks. Then I went with OWC and it worked fine.

In Crucial's defense, the G4 Powerbooks in general were the pickiest machines I can remember when it came to RAM. I've opened hundreds of Apple laptops and Micron is probably the vendor I've seen most for Apple's factory configs - I have to go back to 2005 to dredge up the one issue I had. I've used Crucial many times since without issue.

Agreed. I have a 733MHz Quick Silver in the Basement Vault.

 

[yadmonkey]

Agreed. I have a 733MHz Quick Silver in the Basement Vault.

I had one of those! A assume you kept yours in case you ever need to completely drown out the sound of a nearby shuttle launch.

On that note, I hope my new iMac is as quiet as my Late 2013 iMac!

 

[alycia]

i found this one on amazon i think i going to buy this one OWC

https://www.amazon.com/gp/product/B072MPMMFX/ref=ox_sc_act_title_1?smid=A2W0TEJ3MK1XP5&psc=1

I got 32GB (2x16gb) and it works great in my new 2017 iMac 27". Thank you for the link.

 

[starwager19]

I went ahead and ordered the OWC 64GB kit. Not the cheapest way to go, but it's in stock now (unlike Crucial), and I like supporting OWC who I've had great experiences with for many, many years.

 

[jmantn]

So here’s an interesting thing I’ve noticed:

If you go to this site
https://www.amazon.com/Crucial-16GB...2888&sr=8-2&keywords=crucial+ddr4+32gb+sodimm

and go to the questions section and type in imac you’ll see what appears to be a crucial rep stating that isn’t the part they suggest and the suggested part would be listed soon with a model number CT2K16G4S24AM.

Well that model number when searched on crucial site takes you to
http://www.crucial.com/ProductDispl...externalPartNumber=CT10559858&catalogId=10151

Which says it’s single ranked.
Keep in mind OWC is dual ranked for 32GB and Hynix is dual ranked for larger storage however we don’t know if that’s what Apple is using since most of us elected for 8GB memory so that’s all the info I’ve seen is that the 8GB is single rank.

As of now on Amazon the memory has appeared and it’s showing dual rank and even has a bullet point stating as much however search for the part number from that Amazon listing and crucial says it’s single ranked.

https://www.amazon.com/Crucial-CT2K...&qid=1497482782&sr=1-2&keywords=CT2K16G4S24AM

Any thoughts?

And it literally sold out while I typed this up.

 

[3drteest]

So here’s an interesting thing I’ve noticed:

If you go to this site
https://www.amazon.com/Crucial-16GB...2888&sr=8-2&keywords=crucial+ddr4+32gb+sodimm

and go to the questions section and type in imac you’ll see what appears to be a crucial rep stating that isn’t the part they suggest and the suggested part would be listed soon with a model number CT2K16G4S24AM.

Well that model number when searched on crucial site takes you to
http://www.crucial.com/ProductDispl...externalPartNumber=CT10559858&catalogId=10151

Which says it’s single ranked.
Keep in mind OWC is dual ranked for 32GB and Hynix is dual ranked for larger storage however we don’t know if that’s what Apple is using since most of us elected for 8GB memory so that’s all the info I’ve seen is that the 8GB is single rank.

As of now on Amazon the memory has appeared and it’s showing dual rank and even has a bullet point stating as much however search for the part number from that Amazon listing and crucial says it’s single ranked.

https://www.amazon.com/Crucial-CT2K...&qid=1497482782&sr=1-2&keywords=CT2K16G4S24AM

Any thoughts?

I asked a Crucial rep about that and they said it was a listing error and it will be fixed within a few days. They reiterated that it's single rank.

I also asked OWC why their RAM is dual and Crucial is single for seemingly the same part and they didn't have an answer.

 

[jmantn]

I asked a Crucial rep about that and they said it was a listing error and it will be fixed within a few days. They reiterated that it's single rank.

I also asked OWC why their RAM is dual and Crucial is single for seemingly the same part and they didn't have an answer.

Ok great. I must have missed it but didn’t see anyone mention it was now listed on Amazon... the one they suggest anyways

Been waiting and waiting and literally within four minutes of me seeing it on Amazon it sells out before I can checkout.

20 sold in 4 min. Nice.

 

[3drteest]

Ok great. I must have missed it but didn’t see anyone mention it was now listed on Amazon... the one they suggest anyways

Been waiting and waiting and literally within four minutes of me seeing it on Amazon it sells out before I can checkout.

20 sold in 4 min. Nice.

I missed it too.

It's disappointing too that OWC raised their prices today.

I just bought this one because I'm tired of all the frustration:

https://www.amazon.com/Crucial-CT2K...&qid=1497482782&sr=1-2&keywords=CT2K16G4S24AM

 

[SaSaSushi]

I have this set of Crucial Ballistix Sport ready and waiting here for my new iMac to arrive on Saturday and will report on its performance after testing.

According to reports at Apple's forums, the Ballistix seemed to work fine in the last gen 5k iMac so fingers crossed.

 

[jmantn]

I have this set of Crucial Ballistix Sport ready and waiting here for my new iMac to arrive on Saturday and will report on its performance after testing.

According to reports at Apple's forums, the Ballistix seemed to work fine in the last gen 5k iMac so fingers crossed.

I bought that set as I initially was thinking I’d be receiving my Mac last Friday.

When I realized it wouldn’t be until the end of this week I kept going back and forth whether I should keep it.

Today I decided to return the ballistic ram and already got a refund for when I could buy the crucial from Amazon hence the disappointment from literally missing out on getting the ram the same day I’d get my computer. The ram was in my cart with a delivery estimate of Friday when my computer gets here. Lol now it’s Pending re stock.

 

[Glideslope]

I had one of those! A assume you kept yours in case you ever need to completely drown out the sound of a shuttle launch.

On that note, I hope my new iMac is as quiet as my Late 2013 iMac!

Vacuum sealed in it's original box along with the rest of my retired devices.

 

[SaSaSushi]

Today I decided to return the ballistic ram and already got a refund for when I could buy the crucial from Amazon hence the disappointment from literally missing out on getting the ram the same day I’d get my computer. The ram was in my cart with a delivery estimate of Friday when my computer gets here. Lol now it’s Pending re stock.

Well, that sucks but isn't the Crucial cheaper and 2017 iMac certified? I hope they restock it for you soon.

I'll report on the Ballistix on Saturday. If it fails the test I'll be returning it too.

 

[jmantn]

Same price for each if purchased directly from Amazon. The crucial is in stock on Amazon but only in stock through third parties which if there’s an issue years later can be a problem plus their price is higher.

The ballistics also went up in price as they were 259 USD and now it’s around 275 making the crucial Mac memory now cheaper even if someone paid the third party selling price of 269.

Editrice went up on Crucial’s site as well it was 250 and now it’s 260

 

[hurtmemore]

What's with the discrepancy between these two?

https://www.amazon.com/Crucial-16GBx2-PC4-19200-SODIMM-260-Pin/dp/B072K5NPRM

http://www.crucial.com/usa/en/ct2k16g4s24am

Same model number, crucial's site says single ranked, amazon says dual.

If it really is dual ranked - isn't it actually the same as the 'non-mac' version?

 

[3drteest]

What's with the discrepancy between these two?

https://www.amazon.com/Crucial-16GBx2-PC4-19200-SODIMM-260-Pin/dp/B072K5NPRM

http://www.crucial.com/usa/en/ct2k16g4s24am

Same model number, crucial's site says single ranked, amazon says dual.

If it really is dual ranked - isn't it actually the same as the 'non-mac' version?

I asked a Crucial rep about that and they said it was a listing error and it will be fixed within a few days. They reiterated that it's single rank. But, you never know.

 

[guibo]

does single vs dual really make a difference? apple doesnt list it as a requirement for compatibility?

 

[KnoeSS]

Generally Single Rank Memory is faster than Dual Rank Memory, in laymen’s terms when a computer accesses Single Rank Memory it only has to go around the track once, where are Dual Rank it would have to go around the track twice.

https://www.oempcworld.com/support/singlevsdualram.html

 

[curmudgeonette]

Generally Single Rank Memory is faster than Dual Rank Memory, in laymen’s terms when a computer accesses Single Rank Memory it only has to go around the track once, where are Dual Rank it would have to go around the track twice.

This "track" quote doesn't make any sense at all! Yes, your link used that wording, but it still doesn't make sense.

Dual Rank quite literally means two memory "modules" on one DIMM. Today's CPUs are meant to work with this. The 27" iMac supports dual memory channels. Each channel supports two DIMMs. Each DIMM can have dual ranks. Thus, there can be up to eight groups of memory chips.

Dual Rank can also actually be faster. Today's memory controllers, while they are waiting for data from one group of memory chips, can command a different group to start an access. The more channels, DIMMs, and ranks, the more likely the next access is in a different group.

...

I've been searching through Intel hardware register level documentation and trying to figure out the true maximum memory for desktop Kaby Lake CPUs. The memory controller can only support 4 gigabit and 8 gigabit chips. It also can support 8 and 16 bit wide chips.

8 gigabit DRAM is the current technology level. Thus, Kaby Lake won't support future 16 gigabit DRAM!

Each memory group has to be 64 bits wide. Therefore, 8 bit wide chips are grouped eight at a time. The 16 bit wide chips are only grouped into fours. Thus total system capacity is lower with 16 bit wide chips!

Eight 8 bit wide chips make a group, aka rank, that has 8 GiB capacity. Multiply by eight for the number of channels/DIMMs/ranks as mentioned above. Thus the 27" iMac can only ever have up to 64 GiB of memory. The 21", with only two socket positions (one DIMM per channel,) has an absolute limit of 32 GiB.

The 21" teardown shows DIMMs with 4 memory chips. These will be 16 bit wide chips. At the 8 gigabit technology level, this makes a 4 GiB single ranked module. Thus the two DIMMs of the torn down iMac add up to 8GiB as expected.

...

16 bit wide chips can be arranged in dual ranks, but manufacturers prefer to use the same number of 8 bit wide chips in a single rank configuration.

Expect 4 GiB DIMMs to be made of four 16 bit wide 8 gigabit DRAMs in a single rank configuration.

8 GiB DIMMs will have eight 8 bit wide DRAMs in a single rank.

16 GiB DIMMs must have 16 8 bit wide 8 gigabit DRAMs in dual ranks! This is the only way they can be made today, and also the only configuration supported by Kaby Lake.

 

[guibo]

This "track" quote doesn't make any sense at all! Yes, your link used that wording, but it still doesn't make sense.

Dual Rank quite literally means two memory "modules" on one DIMM. Today's CPUs are meant to work with this. The 27" iMac supports dual memory channels. Each channel supports two DIMMs. Each DIMM can have dual ranks. Thus, there can be up to eight groups of memory chips.

Dual Rank can also actually be faster. Today's memory controllers, while they are waiting for data from one group of memory chips, can command a different group to start an access. The more channels, DIMMs, and ranks, the more likely the next access is in a different group.

...

I've been searching through Intel hardware register level documentation and trying to figure out the true maximum memory for desktop Kaby Lake CPUs. The memory controller can only support 4 gigabit and 8 gigabit chips. It also can support 8 and 16 bit wide chips.

8 gigabit DRAM is the current technology level. Thus, Kaby Lake won't support future 16 gigabit DRAM!

Each memory group has to be 64 bits wide. Therefore, 8 bit wide chips are grouped eight at a time. The 16 bit wide chips are only grouped into fours. Thus total system capacity is lower with 16 bit wide chips!

Eight 8 bit wide chips make a group, aka rank, that has 8 GiB capacity. Multiply by eight for the number of channels/DIMMs/ranks as mentioned above. Thus the 27" iMac can only ever have up to 64 GiB of memory. The 21", with only two socket positions (one DIMM per channel,) has an absolute limit of 32 GiB.

The 21" teardown shows DIMMs with 4 memory chips. These will be 16 bit wide chips. At the 8 gigabit technology level, this makes a 4 GiB single ranked module. Thus the two DIMMs of the torn down iMac add up to 8GiB as expected.

...

16 bit wide chips can be arranged in dual ranks, but manufacturers prefer to use the same number of 8 bit wide chips in a single rank configuration.

Expect 4 GiB DIMMs to be made of four 16 bit wide 8 gigabit DRAMs in a single rank configuration.

8 GiB DIMMs will have eight 8 bit wide DRAMs in a single rank.

16 GiB DIMMs must have 16 8 bit wide 8 gigabit DRAMs in dual ranks! This is the only way they can be made today, and also the only configuration supported by Kaby Lake.

great info thanks!

i see you say 8gb dimms will be single rank. is it at all possible for them to be available dual rank? and would it be an issue, or limit the max amount of RAM?

im asking because most sellers dont readily give dual/single rank info, and i was looking to add 2x8GB.

 

[curmudgeonette]

i see you say 8gb dimms will be single rank. is it at all possible for them to be available dual rank? and would it be an issue, or limit the max amount of RAM?

They could be made with last generation 4 gigabit chips. That would necessitate 16 chips which would have to be arranged in dual ranks.

I think in theory they could also use 16 bit wide 8 gigabit chips, which would have to be in two ranks of four.