Stupid question regarding RAM upgrade in 27" iMac

The Clark

macrumors 6502
Original poster
Dec 11, 2013
355
523
Canada
So I finally pulled the trigger on an iMac and Intend to upgrade the 8gb of ram to 16gb, but I am a little nervous about the procedure. I'm mainly concerned about breaking the ram/imac by putting it in the wrong way. I am not a builder! Is there a sure fire way to put the ram in such as the notch always being on the right/left side or sticker always facing down etc? I was thinking I could just take the old ram put and observe where the notch is and then replicate it with the new Ram but I'm not sure that would work.. also if you have any ram recommendations please do link then below.

Thanks
 

Fishrrman

macrumors Core
Feb 20, 2009
19,402
6,708
I don't have an iMac, but I'll reckon that the RAM DIMMs have a "notch" in them (near the pins), so that they can only go in "one way". You put it into the slot, then gently (emphasis on GENTLY) press it in to lock it in place. Be mindful of the small (and fragile) "keepers" on either side.

I have read, but cannot confirm, that with 4 DIMMs, you need to "alternate" them.
That is like this:
1. original a
2. new a
3. original b
4. new b

But again, I'm not sure about that.

Can someone else in the forum with a 2017 iMac confirm or correct this?
 

bbnck

macrumors 6502a
Mar 19, 2009
567
311
If you bought a 2017 era iMac, it will come with 2x 4 GB DIMMs so if you buy an additional 2x 4 GB DIMMs, just install them into the available slots. On the other hand, if you bought a 2015 iMac, it will have a single 8 GB DIMM preinsalled, so you might want to buy a single 8 GB DIMM to bring the total memory capacity to 16 GB.

Be forewarned that you do need to apply a reasonable, but not excessive, amount of pressure on each side of the DIMM to fully install it. Just properly align the DIMM into the socket and slowly press down equally on each side. It's no different to screwing something in and not going so far as to strip the thread. Use reasonable judgement.

When the DIMM is installed, you may not necessarily hear it click into place but you will feel it.

Follow the upgrade guide here: https://support.apple.comHT201191#27inch2017 (for 2017 era iMac).

This article also explains what orientation the DIMM should face when being installed.
 
Last edited:

The Clark

macrumors 6502
Original poster
Dec 11, 2013
355
523
Canada
Thank you all, I think it will be okay. I ended up ordering 16gb of RAM (separately) instead of two 4gb sticks, so the total should be 24GB all together.. and that's okay right? It doesn't have to be either 8, 16, or 32 correct?
 

rkaufmann87

macrumors 68000
Dec 17, 2009
1,760
38
Folsom, CA
Thank you all, I think it will be okay. I ended up ordering 16gb of RAM (separately) instead of two 4gb sticks, so the total should be 24GB all together.. and that's okay right? It doesn't have to be either 8, 16, or 32 correct?
That is correct. Hopefully you purchased quality RAM, iMacs are VERY sensitive to RAM. I highly recommend Crucial.com or www.macsales.com. Both vendors supply high quality RAM, great service and fair prices. If the RAM you bought gives you trouble, return it ASAP and buy from one of these vendors. They both provide lifetime guarantees on their RAM.
 

mj_

macrumors 6502a
May 18, 2017
801
468
Austin, TX
Macs used to be overly sensitive to RAM but that is no longer the case. The memory controller is now part of the Intel CPU and thus absolutely and 100% identical to every other computer with the same generation CPU out there. The days where Macs were picky regarding RAM sticks are over. That said I agree that cheap RAM can cause a lot of trouble, and that you are on the safe side with quality RAM made by Crucial, Kingston, Samsung, Infineon, or Hynix.
 

colodane

macrumors 6502a
Nov 11, 2012
816
273
Colorado
Thank you all, I think it will be okay. I ended up ordering 16gb of RAM (separately) instead of two 4gb sticks, so the total should be 24GB all together.. and that's okay right? It doesn't have to be either 8, 16, or 32 correct?
I did exactly what you are doing with the additional 16 GB on my 2017 iMac, using Crucial RAM. It worked out fine. Just install them into the two empty slots.

When installing them, be cautious when you are lining them up and getting the orientation right. Then, you may need a fair amount of pressure to make them settle into place. As someone else pointed out, you may or may not hear any "click", but you will definitely feel them seat into the socket when they are completely inserted.
 
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