2013 27in iMac Ram Question!

Nope
You won't be able to use older, slower RAM in your new iMac.

You actually could put it in but all of your RAM would slow down to the slowest RAM module in the computer, so in your case, all of your RAM would clock down to 1333 rather than 1600.

Personally I wouldn't mix RAM speeds.
Check RAM on Amazon, any DDR3 1600 204-Pin will work.
Using 2 RAM slots then 1.5v RAM is ok.
Using 4 RAM slots then 1.35v RAM.

There are a few reports on MacRumors where people try using 1.5v RAM in all 4 slots and their computers sometimes have kernel panics, more often than only using 2 - 1.5v slots.

I installed 4 - 8GB 1.35v sticks in my late 2013 iMac and it has been rock solid.

Using the older iMac's RAM in the new machine is not recommended and might not even work anyway.

See this well-traveled thread for information and advice on upgrading RAM in the Haswell iMac, particularly to 32GB.

Don't just buy any 1.35V RAM. Crucial's DDR3L for the Late 2013 iMac is one of the recommendations known to work.

Although Apple specifies it on the memory upgrade specs page for the Late 2013 iMac, I do not recommend 1.5V RAM in any configuration. Yes, it might work with less than 32GB, but what if you decide you want to upgrade in the future?

Apple's stock RAM is all 1.35V.

Does the latest IMAC 27" Support 1800 or higher bus speed?

thanks
G

technosaints said:

Does the latest IMAC 27" Support 1800 or higher bus speed?

thanks
G

Click to expand...

No intel systems support 1800 or higher. But will it run at 1866? Yes it will if you put the appropriate ram in it. You may (or may not) experience instability issues though. Some people have had lots of trouble with ram - even at 1600MHz - in the 2013 iMacs. Others have not.

2013 27in iMac Ram Question!

SaSaSushi said:

Using the older iMac's RAM in the new machine is not recommended and might not even work anyway.

See this well-traveled thread for information and advice on upgrading RAM in the Haswell iMac, particularly to 32GB.

Don't just buy any 1.35V RAM. Crucial's DDR3L for the Late 2013 iMac is one of the recommendations known to work.

Although Apple specifies it on the memory upgrade specs page for the Late 2013 iMac, I do not recommend 1.5V RAM in any configuration. Yes, it might work with less than 32GB, but what if you decide you want to upgrade in the future?

Apple's stock RAM is all 1.35V.

Click to expand...

Exactly what I was looking for. Thanks for the reply and link.

Would you mind if I PM'd you prior my purchase? People get a little irritated around here with RAM questions but it's my money soooo.

cynics said:

Would you mind if I PM'd you prior my purchase?

Click to expand...

Sure, drop me a line. I'm glad to help.

I have the Crucial 16GB kit the way to me now (CT2K8G3S160BM). Ordered it from Amazon this morning, and it will be here Thursday.

SaSaSushi said:

Apple's stock RAM is all 1.35V.

Click to expand...

The stock RAM is 1.5v

mmomega said:

The stock RAM is 1.5v

Click to expand...

The stock RAM for the Late 2013 iMac is DDR3L 1.35V. I know, I own an iMac which I ordered with 2x8GB sticks. There are a few vendors that Apple utilizes. In my case it is Elpida.

Elpida is now a Micron subsidiary. Crucial is the consumer line for Micron. I highly recommend Crucial RAM for the Haswell iMac and in particular the CT2K8G3S160BM model sold at Amazon.

This is confirmed to work properly. I own it as well and use it in combination with the stock Apple Elpida.

SaSaSushi said:

The stock RAM for the Late 2013 iMac is DDR3L 1.35V. I know, I own an iMac which I ordered with 2x8GB sticks. There are a few vendors that Apple utilizes. In my case it is Elpida.

Elpida is now a Micron subsidiary. Crucial is the consumer line for Micron. I highly recommend Crucial RAM for the Haswell iMac and in particular the CT2K8G3S160BM model sold at Amazon.

This is confirmed to work properly. I own it as well and use it in combination with the stock Apple Elpida.

Click to expand...

The stock iMac (Elpida) RAM is 1.5v. I know this because it won't work in my Haswell Intel NUC, which absolutely requires 1.35v RAM. It won't even boot with 1.5v RAM, period. I tried. No go. Had to buy some Crucial 1.35v RAM to make it work.

I recommend Corsair Vegeance RAM for the iMac 2012/2013. Rock solid with 32GB of it here. I recommend it over the Crucial memory for the sole reason that Crucial should be ashamed of having so many idiotic part numbers, most of which are the same part with a different number.

Confirmed as 1.5v back here, too..

https://forums.macrumors.com/threads/1508691/

WilliamG said:

The stock iMac (Elpida) RAM is 1.5v. I know this because it won't work in my Haswell Intel NUC, which absolutely requires 1.35v RAM. It won't even boot with 1.5v RAM, period. I tried. No go. Had to buy some Crucial 1.35v RAM to make it work.

Click to expand...

I have never heard of a Haswell (Late 2013) iMac shipping with 1.5V RAM. Is yours the Haswell or a 2012 model?

Note the fact that your Haswell NUC requires 1.35V RAM.

The stock Apple RAM that came in my machine is 1.35V. I know it because it says DDR3L right on the label. That, and the fact that both Tech Tool Pro and CPU-Z show this to be the fact as well.

In case you think the label is lying you can look up the part number, EBJ81UG8EFU5-GNL-F

Elpida 8GB PC3-12800 DDR3-1600MHz non-ECC Unbuffered CL11 204-Pin SoDimm 1.35V Low Voltage Dual Rank Memory Module

SaSaSushi said:

I have never heard of a Haswell (Late 2013) iMac shipping with 1.5V RAM. Is yours the Haswell or a 2012 model?

Note the fact that your Haswell NUC requires 1.35V RAM.

The stock Apple RAM that came in my machine is 1.35V. I know it because it says DDR3L right on the label. That, and the fact that both Tech Tool Pro and CPU-Z show this to be the fact as well.

In case you think the label is lying you can look up the part number, EBJ81UG8EFU5-GNL-F

Elpida 8GB PC3-12800 DDR3-1600MHz non-ECC Unbuffered CL11 204-Pin SoDimm 1.35V Low Voltage Dual Rank Memory Module

Click to expand...

Mine is a 2012 model. I didn't notice the 2013 iMac talk (oops). Still, the '13 iMac should work with 1.5v DIMMs...

See here:

https://forums.macrumors.com/threads/1654161/

WilliamG said:

Mine is a 2012 model. I didn't notice the 2013 iMac talk (oops).

Click to expand...

Not a problem.

Still, the '13 iMac should work with 1.5v DIMMs...

Click to expand...

I know the thread you referred to very well. Please browse all the way to the end. I went through the ringer with RAM upgrades for my iMac and I can tell you that none of the 1.5V brands I tried worked at 32GB. In fact, the first 1.35V RAM I tried (TEAM Group, a Taiwanese brand) didn't work either.

The Haswell iMacs are extremely sensitive with RAM, particularly at 32GB.

Also, I don't think Crucial markets so many different model numbers. They do have internal part numbers for the RAM they sell directly but the model Haswell iMac owners want for the Late 2013 iMac, and which works is:

CT2K8G3S160BM (2x8GB package) <- search it at Amazon

CT8G3S160BM <- this is the part number for the individual 8GB DIMM

These off-site threads, here and here are also highly recommended reading for those upgrading RAM on Late 2013 iMacs: