Best way to configure RAM?

1. Your computer has got 4 slots to place memory, so that is not a problem.

2. You should not notice a decrease on the performance compared to 2x8 GB of memory. However, I recommend you to install the new memory horizontally so you will get Dual Channel and its performance will be better. If Apple wants that you buy the memory in the Apple Online Store, I recommend you to purchase it in OWC or Crucial with a cheaper cost and compatible with your iMac > http://www.macsales.com

I assume you are talking about a 27in iMac as the new 21in models don't have user upgradeable RAM.

If that is the case then if this statement was really given to you

was considering just getting a full refund and buying aftermarket RAM, but the Apple CS people said that would void my warranty. I certainly didn't want thatThanks!

it is absolutely false. It is perfectly permissible for a user to upgrade the RAM in any Mac that has end user access to the RAM.

If this was truly said to you you should contact Apple and let them know about it.

You can purchase and upgrade the RAM yourself.

regards

Under normal circumstances getting the memory from a 3rd party is always cheaper then getting it from Apple but in your case you'll need to do some price shopping.

I find OWC both competitive price wise and also very good and making sure you get the right memory for your system. I don;t know what 50% off Apples 8gb will be but you can easily compare that price to what you would pay at OWC.

Of course you have options if you go 3rd party. You could just buy 1 8gb stick instead of 2x4gb. Doing that will depend on both what you are willing to pay and what long term plans you have for the system. If you think you might add more memory in the future then just adding one 8gb stick now will leave you with two empty slots for future expansion. If you go with 2x4gb now you'll have 16gb but only have on empty slot.

So I guess what I am trying to say is there is no right or best way to go here. You need to decide based both on price and configuration what will be best for you.

regards

Go to Crucial.com. They have the best RAM and they actually manufacture it, They are Micron.

Ideally, the RAM should match horizontally, i.e. this screenshot:

So you now have three 8 GB modules? There was a problem with 2010 models which would not boot if there was one empty slot (cannot remember if it related to the top or bottom slots); however, since you do not seem to have a problem, it should be fine (as long as your Mac specs say that it can support more than 16 GB/up to 32 GB?)

FWIW, the way Apple calls the top and bottom slots is counter-intuitive: if you are facing the RAM slots (monitor down), then the 2 x 2 GB (in screenshot) are the original RAM, show correctly as being in the top slots here and when you are looking at them, but, according to Apple, are in the bottom slots (since they are not closest to the monitor).

I found the brand new instructions for the new iMacs here:

http://support.apple.com/kb/HT5540

Here are the instructions for earlier iMacs:

http://support.apple.com/kb/HT3918?viewlocale=en_US&locale=en_US#

Now, I've not seen a 2012 iMac's memory configuration, so I do not know if my remarks are still valid or not. On the previous models, Apple called the slots nearest the display the "top" which, when it is lying screen down and you are looking at all of them, I would call the "bottom" slots.

I'm also not sure if this still applies to the brand new iMacs: Macs have always performed better when memory was installed in matching pairs; and, if you read the instructions, there is mention of using 4 x 4 GB or 4 x 8 GB - populating each slot, or, as default from factory, having 2 slots installed - in other words, always in pairs, rather than only having 1 pair and 1 extra module. So, not knowing the cause of your speed issue with 2 vs. 3 modules, I would guess it may have something to do with that. I'd think it would be fine with 3 modules, but it may be that Apple designed it to work best with either 2 or 4 slots populated. That is assuming that you purchased the correct RAM and they all match.

Sorry babowa, but, how you can tell that "ideally" the RAM must match horizontally? It's not that I don't trust you, in my case this is my configuration untill the local store gets another 8GB stick:

But where can I get official info about that? Thanks!

If you have a recent model Mac, the entire RAM arrangement is a bit confusing because:

on the Mac, they are actually now arranged vertically; however....

if you look at the About my Mac memory display, it still shows them in two rows of two each.

So, the preferred arrangement was that the two upper slots match as well as the two lower slots - installing them in pairs. Now, it would be (from the top) the first and third slots match and the second and fourth.

If you look at my previous post, there was an Apple article that detailed problems if only one bottom slots was occupied. I do not know if there is any problem about one slot not being occupied in the new Macs. And, as you can see, Apple installs RAM in the two top slots (or, now, slot 1 and 3):

Additional notes i5 and i7 Quad Core iMac computers come with both top memory slots populated. These computers will not start up if only a single DIMM is installed in any bottom slot; these computers should operate normally with a single DIMM installed in any top slot. Core Duo iMac computers should operate normally with a single DIMM installed in any slot, top or bottom. ("Top" and "bottom" slots refer to the orientation of the slots in the pictures below. "Top" refers to the slots closest to the display; "bottom" refers to the slots closest to the stand).

And, here was their recommendation:

For best performance, fill both memory slots, installing an equal memory module in each slot.

Now, I cannot say with 100% certainty that this still applies, but people in general still recommend it.

Well thanks for all the info!!!

You're welcome!