RAM upgrade in mid 2011 27" iMac.

B'Tol

macrumors newbie
Original poster
Jan 11, 2014
3
0
Hi all - new to the forums as looking to get some answers on RAM upgrades! :)

I own a mid-2011 27" iMac, 3.4 GHz i7 AMD Radeon HD 6970M 2048 MB graphics, and 1TB hard drive.

I am looking to upgrade the RAM from the present 2x2 GB 1333 MHz DDR3 and going up to 16gb or possibly even higher.

I was hoping you guys could answer a couple of questions.

Is it possible to simply use 2 x 8GB of ram, or do I need to spread the 16GB across all four slots, so 4 x 4GB?

Also - I have read a few examples of folks using DDR3-1600 rather than DDR3-1333. How safe is this?

Also - is it possible to go higher than 16GB on this model? And do all allocations have to be even? So could I house 2 x 4GB in the top slots, and 2 x 2GB in the bottom for example?

I hope this all makes sense! Being a relative newcomer to the mod side of things I was hoping this would be the place for clarification.

Thanks in advance.
 

Xer

macrumors newbie
Jan 17, 2009
16
0
According to Apple your iMac can only receive up to 16GB, but that's not always the case.
Actually your iMac can take up to 32GB (8GB x 4).

I would recommend getting 16GB of RAM (4GB x 4), but if you really need to top 32GB, it should work just fine.

As far as 1333MHz vs 1600Mhz, your iMac can take 1600 but it will automatically decrease the memory speed to 1333, so it doesn't give you anything there, it's better to buy a straight 1333 RAM (should be cheaper too).

You can try purchasing from OWC
http://eshop.macsales.com/shop/memory/iMac/2011/DDR3_21.5_27

Good luck ! :):)
 

B'Tol

macrumors newbie
Original poster
Jan 11, 2014
3
0
Thank you sir, much appreciated!

Can I not do 16GB via two 8GB in the top slots? Does it HAVE to be split over the 4 separate slots?

Does anyone now of a UK dealer other than Crucial?
 
Last edited:

Xer

macrumors newbie
Jan 17, 2009
16
0
Thank you sir, much appreciated!

Can I not do 16GB via two 8GB in the top slots? Does it HAVE to be split over the 4 separate slots?

Does anyone now of a UK dealer other than Crucial?
You can, it's just not really recommended as far as Apple's concern.
 

macthefork

macrumors 6502
Feb 2, 2013
467
7
You could also put 2x8GB Modules in the top slots, and the existing 2x2 modules in the bottom slots for a total of 20GB. This would also work fine.

It's best not to mix speeds of RAM, even though it will work. You probably wouldn't notice the difference with it running at the slower speed, however.
 

Blueline111

macrumors newbie
Dec 26, 2013
10
0
You could also put 2x8GB Modules in the top slots, and the existing 2x2 modules in the bottom slots for a total of 20GB. This would also work fine.

It's best not to mix speeds of RAM, even though it will work. You probably wouldn't notice the difference with it running at the slower speed, however.
I have 2011 21" iMac with 4 gigs RAM (2x2). I also want to add 16 gigs for a total of 20 gigs. My thinking is 2x8 would be best to possibly add more when prices decrease.

Does it really make a difference which memory slots the different size modules go? If so, are the "top slots" the BANK 0/DIMM0 & BANK1/DIMMO where the 2x8 modules go?
Thanks!
 

Blueline111

macrumors newbie
Dec 26, 2013
10
0
My new memory should be here tomorrow and I want to be sure to install it correctly.

Does it really make a difference which memory slots the different size modules go? If so, are the "top slots" the BANK 0/DIMM0 & BANK1/DIMMO where the 2x8 modules go?

Will someone please let me know about the "top slots".
Thanks!
 
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