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iMac 2017: Warning to those adding their own RAM?

A

Anathem

macrumors newbie
Original poster
Jun 11, 2012
10
36
So here's an answer from Apple Care that should unsettle anyone considering one of the new iMacs.

My question to them: If I were to buy the 8GB base model of the new 27 Inch iMac now, could I install my own RAM later to take it up to 64GB?

Their reply: If I order the base 8GB model, while I could later install up to 64 Gb in the 4 available slots, the most that will actually be useable is limited to 16GB (for a total of 24GB).

I didn't understand the explanation (I'm not techie), but it seemed to be because the original RAM was 2x4GB each, and therefore it could only deal with multiples of 4GB in expansions.

My (possibly mistaken) takeaway: If you order the new 27 inch iMac with 8GB of RAM, the most you can ever useably upgrade it to is 24 GB(!)

Not so, surely? Can someone who knows advise?
 
Anathem said:
So here's an answer from Apple Care that should unsettle anyone considering one of the new iMacs.

My question to them: If I were to buy the 8GB base model of the new 27 Inch iMac now, could I install my own RAM later to take it up to 64GB?

Their reply: If I order the base 8GB model, while I could later install up to 64 Gb in the 4 available slots, the most that will actually be useable is limited to 16GB (for a total of 24GB).

I didn't understand the explanation (I'm not techie), but it seemed to be because the original RAM was 2x4GB each, and therefore it could only deal with multiples of 4GB in expansions.

My (possibly mistaken) takeaway: If you order the new 27 inch iMac with 8GB of RAM, the most you can ever useably upgrade it to is 24 GB(!)

Not so, surely? Can someone who knows advise?
Click to expand...
According to https://www.apple.com/imac/specs/ the 27" iMac has 4 user-accessible RAM slots. You can put 64GB in any of them.
 
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chrfr said:
According to https://www.apple.com/imac/specs/ the 27" iMac has 4 user-accessible RAM slots. You can put 64GB in any of them.
Click to expand...

That doesn't necessarily contradict what I was told (you can physically add 64 GB), but do we know for a fact that the iMac will be able to use all 64GB?

The AppleCare rep I talked to put me on hold for 10 minutes to check his answer with a supervisor: the confirmation was that 24GB is all the machine would be able to access - no matter much was added - if 8GB is what you started with.

Very happy to be told this is not true :)
 
Anathem said:
That doesn't necessarily contradict what I was told (you can physically add 64 GB), but do we know for a fact that the iMac will be able to use all 64GB?

The AppleCare rep I talked to put me on hold for 10 minutes to check his answer with a supervisor: the confirmation was that 24GB is all the machine would be able to access - no matter much was added - if 8GB is what you started with.

Very happy to be told this is not true :)
Click to expand...

This must be not true!

I can't imagine why you would do this.(beging Apple)
 
KnoeSS said:
This must be not true!

I can't imagine why you would do this.(beging Apple)
Click to expand...

This is obviously not true. The people at Applecare do not get advanced information about the products. They don't find out until we find out.

What is true is that you cannot both use apples original 8 GB of RAM and simultaneously upgrade the machine to 64 GB of RAM. You have to take their memory out and throw it away (or give it away, or sell it for a couple of bucks) in order to install four of the 16 GB memory sticks.
 
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So if the base 27" starts with 8, you can only add 4 of the 4GB RAM sticks within the user accessible slots (to get the total useable RAM of 24GBs)?
 
Anathem said:
That doesn't necessarily contradict what I was told (you can physically add 64 GB), but do we know for a fact that the iMac will be able to use all 64GB?

The AppleCare rep I talked to put me on hold for 10 minutes to check his answer with a supervisor: the confirmation was that 24GB is all the machine would be able to access - no matter much was added - if 8GB is what you started with.

Very happy to be told this is not true :)
Click to expand...
Their response applies to the old model. If you get one with 2*4GB RAM, you have two slots left for 8GB max in each. Hence their 24GB figure.
Of course you can remove the original DIMMs and use 4*8GM DIMMs.
On the newer model, you can use 4*16GB DIMMS.
 
jeanlain said:
Their response applies to the old model. If you get one with 2*4GB RAM, you have two slots left for 8GB max in each. Hence their 24GB figure.
Of course you can remove the original DIMMs and use 4*8GM DIMMs.
On the newer model, you can use 4*16GB DIMMS.
Click to expand...

Exactly what I was about to type! Except that the lowest tier new 27" also appears limited to 32GB for 24GB max if the original 2*4GB is left in place.
 
You just bin the original memory and fit all new sticks which match in all four slots. You'd be crazy to leave the original memory in place and expect it not to play up with third party sticks.
I always get the minimum amount of memory, bin it and then upgrade with all Kingston sticks, if you're spending £2k a few hundred extra on decent memory is a wise investment.
 
Good in theory, but in practice you're still better off replacing all the memory with the same, especially as Apple memory is usually the low end of the quality spectrum even though you pay top dollar for it.
 
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dborod said:
I would be curious to see evidence of such a claim, as it does not agree with my experience.
Click to expand...

The evidence is in using a machine with mixed RAM and getting random crashes/lockups. If you've never experienced this then you are a very lucky chap indeed.

Bottom line is that the memory being perfectly in snyc is the basic foundation of a stable machine and mixing and matching memory modules is like playing Russian roulette, you're better off just spending the extra money, selling the Apple memory on EBay and be happy that it's one more potential problem averted.
 
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dborod said:
I would be curious to see evidence of such a claim, as it does not agree with my experience.
Click to expand...

I would also like to see such evidence. It can happen, but ram from a reputable source is very unlikely to have any issues directly related to being mixed in with Apple ram.
 
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Sigh, whatever guys.
You slap in your extra RAM and be thankful you've saved a few bucks and I'll replace all the RAM and be happy I was getting a stable machine, there you go sorted....
 
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Apple only uses RAM from Samsung, Hynix and Micron, the three big remaining vendors who have their own chip production. All other vendors buy them from these three, so how should they be better? In my experience the third party memory is the troublemaker, but in most cases changing all modules should avoid this.
 
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Georgio said:
Sigh, whatever guys.
Click to expand...

You said there was evidence and we were just interested in seeing what it is so we can learn. Evidence can't be "I don't do it, and I don't have trouble, therefore if you do it you'll have problems" though. If you do have any evidence I'd still be interested in reading it so send it over to my inbox :). Never hurts to have more information at your disposal.

In the meantime, I think the rep maybe just misunderstood or was wrong in their information. Any 27" config will recognize up to the stated 64gb of ram, but you'll need to replace the stock ram chips. There's a couple other threads with conflicting info from Apple and Apple docs on the new ram and what type it uses, so my guess is that (unfortunately) they just don't have all the info updated yet but will in the coming days.
 
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There is indeed a higher risk of mixed RAMs not syncing with each other or even creating kernel panics. While it is not a rarity, there are still examples of them working fine in all likelihood. My experience with Macs that have more than 2 slots but I must buy with stock RAMs, is to wait for it to come, confirm with absolute certainty how many slots are empty, then and only buy and put in after market ones in the empty slots first. You only got time to lose if this doesn't work out and you have to throw the stock sticks away. Like the case of this 2017 iMac, I plan to buy 2 sticks of 16GB on top of the lowest config of 4+4GB so if lucky I get 40GB in total, if not I am down to 32GB for a while, and whenever I feel like to I can add the remaining 32 to max it at 64 later.
 
Anathem said:
So here's an answer from Apple Care that should unsettle anyone considering one of the new iMacs.

My question to them: If I were to buy the 8GB base model of the new 27 Inch iMac now, could I install my own RAM later to take it up to 64GB?

Their reply: If I order the base 8GB model, while I could later install up to 64 Gb in the 4 available slots, the most that will actually be useable is limited to 16GB (for a total of 24GB).

I didn't understand the explanation (I'm not techie), but it seemed to be because the original RAM was 2x4GB each, and therefore it could only deal with multiples of 4GB in expansions.

My (possibly mistaken) takeaway: If you order the new 27 inch iMac with 8GB of RAM, the most you can ever useably upgrade it to is 24 GB(!)

Not so, surely? Can someone who knows advise?
Click to expand...
[doublepost=1517989169][/doublepost]Does anyone really know whether this configuration will be suitable or compromised in any way (in line with the OPs question):
I too have a new iMac 2017 i5 3.5GHz machine, and plan to upgrade the 2 x 4 GB ram with the following configuration:

1. 4 GB Original RAM 2. 4 GB Original RAM
3. 16 GB Crucial RAM 4. 16 GB Crucial RAM

The total is 40 GB, but will the new 16 GB x 2 be compromised by retaining the original 4 GB x 2 in the slots?
 
michaelnic said:
[doublepost=1517989169][/doublepost]Does anyone really know whether this configuration will be suitable or compromised in any way (in line with the OPs question):
I too have a new iMac 2017 i5 3.5GHz machine, and plan to upgrade the 2 x 4 GB ram with the following configuration:

1. 4 GB Original RAM 2. 4 GB Original RAM
3. 16 GB Crucial RAM 4. 16 GB Crucial RAM

The total is 40 GB, but will the new 16 GB x 2 be compromised by retaining the original 4 GB x 2 in the slots?
Click to expand...

No

Edit: assuming they are the same speed, lowest defaults
 
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Georgio said:
Good in theory, but in practice you're still better off replacing all the memory with the same, especially as Apple memory is usually the low end of the quality spectrum even though you pay top dollar for it.
Click to expand...

Absolute hogwash.

Apple's RAM upgrades are ridiculously overpriced. This is true. The RAM Apple uses being "low end of the quality spectrum" is not. The Micron, Hynix and Samsung parts Apple uses are excellent quality modules.

Also, as long as you get good quality PC4-19200 RAM from a quality maker like Crucial (the consumer division of Micron) or the equivalent, there should be no problems adding third party RAM to Apple's own.

I added 32GB of Crucial Ballistix to the 8GB of Apple-shipped Micron for a total of 40GB in my 2017 iMac and it has been running flawlessly for 8 months now.

This thread is all you need for information about RAM upgrades in the 2017 iMac.
[doublepost=1517998183][/doublepost]
michaelnic said:
The total is 40 GB, but will the new 16 GB x 2 be compromised by retaining the original 4 GB x 2 in the slots?
Click to expand...

No, it will not and I highly recommend Crucial.
 
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Well, I ran my with the original stick + 2 x 8 GB Kingston for a few weeks. No problem at all. Replaced the originals when the Kingston got back in stuck.
 
Baunkjaer said:
Well, I ran my with the original stick + 2 x 8 GB Kingston for a few weeks. No problem at all. Replaced the originals when the Kingston got back in stuck.
Click to expand...

Would that be Kingston HyperX? That is known to be incompatible with Apple's stock RAM because it is actually overclocked and not standard PC4-19200.

It is covered in detail in the thread I linked to in my previous post.
 
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