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RAM upgrade 27 iMac Late 2013

futurase

futurase

macrumors member
Original poster
My iMac has 8gb of ram from apple with 2 4gb chips. There are 4 slots so can I add 2 8gb chips from Crucial to add up to 24gb total or do I have to take out OEM memory before I can put Crucial in?

Just got new iMac other day. My old early 2009 iMac only had two slots so mixing ram was not an option.

I'm betting answer is I can't unless I buy same exact RAM from Apple. 🙁
 
You absolutely can add 2 8GB sticks from Crucial to yield 24GB total.

Quick and easy. You can use the Crucial website to select the correct RAM.
 
You can mix brands of ram? Anyone currently doing it that has had no kernel panics?
 
I put 2x 4gb sticks in from crucial about 3 weeks ago, been running fine, all 4 slots now occupied. You absolutely do not take out the existing memory.
 
futurase said:
You can mix brands of ram? Anyone currently doing it that has had no kernel panics?
Click to expand...
YEs you can mix brands of ram. What matters is you get memory that has the same specs as what you already have. MY late 2009 iMac has 2 different brands of memory in it.
 
Using the one from Apple (2 x 4), and (8 x 2) from Crucial with a total of 24 GB on my late 2012 27 iMac.


Using a standard original 2 GB from Apple, and a 4 GB from Kingston on my non retina macbook pro 13 inch.
 
Tumbleweed666 said:
I put 2x 4gb sticks in from crucial about 3 weeks ago, been running fine, all 4 slots now occupied. You absolutely do not take out the existing memory.
Click to expand...

You can and crucial advised me to.

I added 2 x 8 to the 2 x 4 Apple installed.

Crucial advised me to swop the locations as the 2 x 8 would be addressed first before the 2 x 4 by doing this.

I checked this with other gurus around included here and they said Crucial were quite correct. Even though the improvement by doing this would not be great.
 
richest said:
You can and crucial advised me to.

I added 2 x 8 to the 2 x 4 Apple installed.

Crucial advised me to swop the locations as the 2 x 8 would be addressed first before the 2 x 4 by doing this.

I checked this with other gurus around included here and they said Crucial were quite correct. Even though the improvement by doing this would not be great.
Click to expand...

When I said you don't take it out I thought you meant you discarded it ! 😱 Its only in this post you used "swap" instead of "take out". Very different things

Also, in my situation, adding 2 more 4GB with existing 4GB there would be no point swapping the order they are in compared to having two 4GB and two 8GB. If Crucial say so, I'm certainly happy to believe there is a small advantage to having the 8GB modules first so swapping them (and not removing) is OK.


Here's what I bought
Qty: 1 CT4951625
Part Number: CT2C4G3S160BMCEU
Description: 8GB Kit (4GBx2), 204-pin SODIMM Upgrade for a Apple iMac (27-inch, Late 2013) System

I chose that simply by going through the advisor function on the crucial website.
 
Mixing ram is fine - the slowest ram in the system will make all the ram run at the same speed.. Talking even down to a CAS level, the RAM controller is designed to normalize all ram down to the same exact speeds.
 
Diversion said:
Mixing ram is fine - the slowest ram in the system will make all the ram run at the same speed.. Talking even down to a CAS level, the RAM controller is designed to normalize all ram down to the same exact speeds.
Click to expand...

Its more complicated than that.

If you mix 1600MHz CL11 Apple ram with 1600MHz CL10 other ram, you will end up running at 1333MHz, i.e. slower than either.
 
Chippy99 said:
Its more complicated than that.

If you mix 1600MHz CL11 Apple ram with 1600MHz CL10 other ram, you will end up running at 1333MHz, i.e. slower than either.
Click to expand...

Why wouldn't it just from all ram at CL11/10 instead of dropping eveything to 1300?
 
Diversion said:
Why wouldn't it just from all ram at CL11/10 instead of dropping eveything to 1300?
Click to expand...

No idea, but that's what it does. It finds the fastest speed both rams can run at CL10. Which for Apple ram is 1333. Why it doesn't just run both at CL11, I don't know.

If you put CL9 ram in with the Apple ram, it might well drop lower than 1333.
 
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