Sidebar Sidebar
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

RAM Question

That's disappointing. I wonder if it had to clock down to deal with latency differences or something?
 
orlandocano said:
So I got the corsair vengeance 1866 mhz sticks... 2 x 8gb to be exact.. i left the original apple ram in there, expecting it to all work at 1866... Instead, it recognized all 24gb of ram, but the system under clocked all of it to 1600... This is what it says in the RAM overview:
24 GB 1600 MHz DDR3

So it seems that unless you match the 1867 mhz of the original apple ram, and you leave the apple sticks in there.. it under clocks all your ram down to 1600 MHz.. which is a HUGE bummer! Oh well.. time to try and sell my original apple ram and buy some more 3rd party stuff! huge huge bummer =(
Click to expand...
I'm not surprised:

Alesc said:
[...]
On previous gen iMacs, if you mix Apple memory (1600 MHz, CL11) with 1600 MHz CL9 memory, the modules all run at 1333 MHz CL9 (because Apple modules can't support CL9 at 1600 MHz).
Click to expand...
 
As expected, I took out the original apple ram and now it's showing 16gb 1867 MHz. I am ok with 24gb so I am ordering the 8gb crucial ballistix kit which has the same exact specs as my corsair vengeance kit. It's only $54 and available on prime right now!
 
orlandocano said:
So I got the corsair vengeance 1866 mhz sticks... 2 x 8gb to be exact.. i left the original apple ram in there, expecting it to all work at 1866... Instead, it recognized all 24gb of ram, but the system under clocked all of it to 1600... This is what it says in the RAM overview:
24 GB 1600 MHz DDR3

So it seems that unless you match the 1867 mhz of the original apple ram, and you leave the apple sticks in there.. it under clocks all your ram down to 1600 MHz.. which is a HUGE bummer! Oh well.. time to try and sell my original apple ram and buy some more 3rd party stuff! huge huge bummer =(
Click to expand...
why would you leave apple memory in there in there if not same speed as 1867 anyway,
 
Dominican said:
why would you leave apple memory in there in there if not same speed as 1867 anyway,
Click to expand...

Because someone on this thread said they spoke to an apple rep and was told that 1866 and 1867 would work fine together.. if anything, most of us assumed it would all run at 1866... I am not sure anyone here expected it to drop down to 1600 considering both apple ram and corsair ram are faster than 1600 (I could be wrong.. it just just what I gathered from reading all 12 pages of this thread)
 
orlandocano said:
Because someone on this thread said they spoke to an apple rep and was told that 1866 and 1867 would work fine together.. if anything, most of us assumed it would all run at 1866... I am not sure anyone here expected it to drop down to 1600 considering both apple ram and corsair ram are faster than 1600 (I could be wrong.. it just just what I gathered from reading all 12 pages of this thread)
Click to expand...

Is there any real world difference between the 1866 vs 1867? I got this one. From anyone with experience would know if this RAM has good speed? I can still cancel my order. Thanks for anyones input.

4CDS38b.jpg
 
Textureboy said:
Is there any real world difference between the 1866 vs 1867? I got this one. From anyone with experience would know if this RAM has good speed? I can still cancel my order. Thanks for anyones input.

4CDS38b.jpg
Click to expand...
It's the same. It's 1866.6mhz, Apple and OWC just round it off. Although now that it's been proven there is a slight performance boost from 2300mhz ram you are better off getting the cheaper Kingston.
 
The iMac ships with 1866MHz ram (Hynix hmt451s6afr8a-rd). Apple rounds up and calls it 1867MHz. OWC is also using “1867MHz” to match Apple's terminology despite the manufacturer of the ram Hynix referring to it as 1866MHz. So yes they are the same thing.
 
Alesc said:
I'm not surprised:
Click to expand...

I am confused... again. I was under the impression from this thread, and a couple of articles I've read, that 1866 was actually 1866.6 mhz and was sometimes referred to as 1867 and therefore behaved the same.

If the RAM that orlandocano added was 1866 why/how does it average out to 1600 mhz?

I purchased this crucial to add to the stock apple 8GB, and am hoping that it was the right move.
 
As an Amazon Associate, MacRumors earns a commission from qualifying purchases made through links in this post.
PunkRawkPurl said:
I am confused... again. I was under the impression from this thread, and a couple of articles I've read, that 1866 was actually 1866.6 mhz and was sometimes referred to as 1867 and therefore behaved the same.

If the RAM that orlandocano added was 1866 why/how does it average out to 1600 mhz?

I purchased this crucial to add to the stock apple 8GB, and am hoping that it was the right move.
Click to expand...
As someone above has mentioned, it could have to do with the CAS latency. I have read that you can mix latencies and many have done so successfully. But the iMac may not recognize the latency of the ram you bought or something could be going on with adjusting for the differences between the two different latencies. The stock ram is CL13 and so is the crucial you just bought so that is a good match.
 
As an Amazon Associate, MacRumors earns a commission from qualifying purchases made through links in this post.
KRMac said:
The stock ram is CL13 and so is the crucial you just bought so that is a good match.
Click to expand...
thank you for your reply. I have learned so much in the last couple of days. I really am paying attention. ;)
My iMac won't be here until Tuesday... so I will do my best to just sit back and not think about RAM until then.
 
Textureboy said:
Is there any real world difference between the 1866 vs 1867? I got this one. From anyone with experience would know if this RAM has good speed? I can still cancel my order. Thanks for anyones input.

4CDS38b.jpg
Click to expand...



It's still not clear but from what I have seen mixing this ram that you got with Apple Ram will work BUT your ram speed drops to 1600 MHZ. My iMac and ram will be here tomorrow so I can test this but for now it's just what's been said in this thread
 
jcr918 said:
It's still not clear but from what I have seen mixing this ram that you got with Apple Ram will work BUT your ram speed drops to 1600 MHZ. My iMac and ram will be here tomorrow so I can test this but for now it's just what's been said in this thread
Click to expand...

Again:

- JEDEC standard is 1866 MHz (or PC3-14900). The actual frequency is 1866.6666667777 (1866 + 2/3) MHz. Apple marketing at work here.
- 1866 MHz = 1867 MHz
- DDR memory is accessed in pairs by the memory controller. So Slot A+B = channel 1, slots C+D = channel 2.
- Don't mix and match SODIMMs with different clocks and CAS latencies. DDR controllers usually have two channels and to operate efficiently, it's recommended to have identical modules in all four slots. A config of:
Slot A: 4GB Apple SO-DIMM @ 1866 MHz (or 1600 MHz)
Slot B: 4GB Apple SO-DIMM @ 1866 MHz (or 1600 MHz)
Slot C: 8 GB Brand X SO-DIMM @ 1866 MHz (or 1600 MHz)
Slot D: 8 GB Brand X SO-DIMM @ 1866 MHz (or 1600 MHz)

is ok. I would also keep the Apple SO-DIMMs in the lower slots.

AFAIK, the original 1600 MHz DDR3 modules were CL11, NON-ECC, DDR3L (@ 1.35V).

Looks like OWC is selling 1866 MHz modules with CL11 for the 2015 models.
 
  • Like
Reactions: PunkRawkPurl
KRMac said:
As someone above has mentioned, it could have to do with the CAS latency. I have read that you can mix latencies and many have done so successfully. But the iMac may not recognize the latency of the ram you bought or something could be going on with adjusting for the differences between the two different latencies. The stock ram is CL13 and so is the crucial you just bought so that is a good match.
Click to expand...
It is because of CAS latency indeed: I don't know why, but the controller prioritize CL over speed. When you mix CL13 and CL10 modules, the controller runs all modules @CL10, and to do so, it must slows down the "Apple RAM" module, which can't support CL10 at 1866/1867 MHz. So everybody runs @ 1600 CL10...

That's why when we learned the "Apple RAM" was CL13 I told you to buy 1866 MHz CL13 modules if you mix with stock RAM, and to take faster modules (frequency or low latency) if you remove stock RAM. :)
 
Hi everyone,

I ordered some Crucial Balistix 7 days ago for my new iMac but it still hasn't been dispatched as they're apparently waiting for a new shipment. My new iMac is here now and I'm thinking of other alternatives.

Would this RAM be ok for my iMac?

http://www.amazon.co.uk/dp/B00VMCUBK4?tag=wwwkingston07-21

or

http://www.amazon.co.uk/dp/B00KQCOV5C?tag=wwwkingston07-21

Any help or advice on what to go for would really help.

I work writing music so are there any best choices?

I'm not looking to keep any of the stock RAM.

Kenny
 
As an Amazon Associate, MacRumors earns a commission from qualifying purchases made through links in this post.
kennyp76 said:
Hi everyone,

I ordered some Crucial Balistix 7 days ago for my new iMac but it still hasn't been dispatched as they're apparently waiting for a new shipment. My new iMac is here now and I'm thinking of other alternatives.

Would this RAM be ok for my iMac?

http://www.amazon.co.uk/dp/B00VMCUBK4?tag=wwwkingston07-21

or

http://www.amazon.co.uk/dp/B00KQCOV5C?tag=wwwkingston07-21

Any help or advice on what to go for would really help.

I work writing music so are there any best choices?

I'm not looking to keep any of the stock RAM.

Kenny
Click to expand...

Those are slower than the stock ram Apple provides.

http://www.amazon.com/gp/aw/d/B00NTQ0GOM/ref=psd_mlt_nbc_B00KQCOV5C_r

If u can afford to get those.
 
As an Amazon Associate, MacRumors earns a commission from qualifying purchases made through links in this post.
gsingham said:
Those are slower than the stock ram Apple provides.

http://www.amazon.com/gp/aw/d/B00NTQ0GOM/ref=psd_mlt_nbc_B00KQCOV5C_r

If u can afford to get those.
Click to expand...

Cheers, they are only around £8 more than what I was paying for the Crucial RAM.

So these would be the best I could get? http://www.amazon.co.uk/Kingston-HyperX-Impact-SODIMM-Memory/dp/B00NTQ0GOM

I was going to get 32gb, but after looking at my activity on Activity Monitor I noticed I wasn't hitting anywhere near that, so may just get 16gb for now. Would it be ok just to fit the 16gb and leave the other banks spare for now until I decide I need more RAM or does it have to all be filled out?

Thanks again for your answer. Going to order some now.
 
Last edited:
As an Amazon Associate, MacRumors earns a commission from qualifying purchases made through links in this post.
kennyp76 said:
Cheers, they are only around £8 more than what I was paying for the Crucial RAM.

So these would be the best I could get? http://www.amazon.co.uk/Kingston-HyperX-Impact-SODIMM-Memory/dp/B00NTQ0GOM

I was going to get 32gb, but after looking at my activity on Activity Monitor I noticed I wasn't hitting anywhere near that, so may just get 16gb for now. Would it be ok just to fit the 16gb and leave the other banks spare for now until I decide I need more RAM or does it have to all be filled out?

Thanks again for your answer. Going to order some now.
Click to expand...

Yes u can leave them empty.
 
As an Amazon Associate, MacRumors earns a commission from qualifying purchases made through links in this post.
Textureboy said:
Is there any real world difference between the 1866 vs 1867? I got this one. From anyone with experience would know if this RAM has good speed? I can still cancel my order. Thanks for anyones input.

4CDS38b.jpg
Click to expand...

I bought this from Amazon, installed it in my new late 2015 iMac yesterday along with the stock RAM. It shows that I have 24 GB 1867 MHz DDR3.
 
These should be OK, right?
G.SKILL Ripjaws Series 16GB (2 x 8G) 204-Pin DDR3 SO-DIMM DDR3L 2133 (PC3L 17000) CL 11-11-11-31 1.35V Laptop Memory Model F3-2133C11D-16GRS

Can't find the Kingston in Australia so that's the closest 2133 ram I could find... Or are the Crucial Ballistix Sport / Kingston HyperX Impact better in regards to how they handle heat ?
 
Fine to know, thank you.

However, it is interesting that Crucial / Kingston to not provide until now detailed information about the suitable ram.

Very interesting is also to see the Apple definition of the specifications in the iBooks manual about the Late-2015 iMac (Page 74):

PC3-15000
Unbuffered and nonparty
204-pin 1867Mhz DDR3 SDRAM


PC3-15000 - what the hell is that?
 
You must log in or register to reply here.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.
Top Bottom
Back