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Model A1419 / EMC 3070 / Mid 2017 / 3.4, 3.5 or 3.8 GHz Core i5 or 4.2 GHz Core i7 Kaby Lake Processor (ID iMac18,3) / Retina 5K display. Refer to the older iMac Intel 27" Retina 5K Display (Late 2014 & 2015) guides as the system is very similar.

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RAM upgrade issue for iMac 2017

Hello,

I purchased OWC RAM of 4GB, 2400 MHz and tried in my iMac. It works fine. However I cannot use all 4 slots at a time, iMac doesn't boot. Plz help

I tried these:

1. Both new RAM (4GB+4GB)-Boots fine

2. Both Old RAM(4GB+4GB)-Boots fine

3. One old & one new-Boots fine

I confirmed that all 4 slots work fine. All 4 RAMs work fine

It is just that I cannot add more than 2 RAM at a time

The following combinations too, work fine.

1,3 slot-Boots fine

1,4 slot-Boots fine

2,3 slot-Boots fine

2,4 slot-Boots fine

Configuration is 3.8Ghz intel core i5,

8GB 2400MHz

18,3

Thanks

Rajesh

Update (07/11/2018)

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Added RAM Pics

Update (07/11/2018)

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Back side is here

Answer this question I have this problem too

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Can you get a snap of the bare chip side (only need one stick) as I wanted to check the chips them selves also do your other sticks (both sides) so we can see whats different.

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How much do you intend on putting in? and what type of ram? Check compatibility

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Take a snapshot of the RAM labels so we can read them Somethings not right here. Adding images to an existing question

The needed modules are: 260-pin PC4-19200 (2400 MHz) DDR4 SO-DIMM's. Which is what you stated you had. All I can think of it maybe mis-marked.

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Fudge! Only top side has the chips ;-{ So I guess we can't get the chip info without pulling back the label which you don't want to do as you'll need to return them. Tell OWC they don't work! I suspect they are mis-marked or just the wrong type.

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Thanks, Dan for your efforts. However as I mentioned early, the RAM chips do work. It is detected perfectly by iMac. What issue I have is I cannot add all 4 RAM slots together. Even one of these RAMs and originally installed iMac RAM also work in combination. What issue is I annot add more than 2 RAMs. Even though all 4 slots of my iMac do work !!

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Well... It's not that simple ;-{ While the chips may work in a pair or even in different slots (banks) there are additional settings within the modules that can mess you up when you've put all four in. Thats why I wanted to see the chips them selves to compare what you have and what OWC is offering you. By looking up the discreet memory chips we can check their values and see if they should play together.

For the sake of argument lets say the chips (modules) are OK and we know the holders are as well then whats left? This gets into the address lines of the holders being wired to the PCH and CPU chips. The high order address line/s maybe defective on the logic board. So when you populate the memory were the address line is needed the RAM fails. This would be extremely rare but its possible! At that point the logic board would need to be replaced.

While you may not like hearing this maybe its best to put the original RAM back in and then bring the system into an Apple Store and ask them to add the RAM. Lets see if they can (I wouldn't tell them you tried). If they can't then they should fix the system under warranty as it's clearly something internal thats defective!

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rajesharm will be eternally grateful.
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