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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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iMac won't boot after RAM upgrade

Hi

I installed 64GB of RAM into my iMac 4 x 16GB

After the upgrade the system fails to boot. I can hear the hard drive, however the screen is off, with the old RAM the iMac works as expected.

I have verified that the RAM is compatible and should work with my iMac.

Any solution to get the iMac to work with the new RAM?

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Not much can be said without knowing the configuration. Some boards and processors have limitations on RAM size and speed, should also check if is it buffered or unbuffered, EDO or SD RAM. Try inserting a single module at a time.

Hi

I have the same problem. After installing 2 additional RAM sticks the iMac won't start anymore. In my case I could isolate the problem to be related to the 4th RAM socket.

If I keep the topmost RAM slot empty and I put some of my RAM sticks in the other three slots the iMac will start.

But if I install a RAM module in the 4th slot the iMac won't start anymore (even with the RAM modules from apple initially installed in slot 1+3).

Can it be that a RAM slot is broken on a new machine ???

Thanks for any help

Andreas

I have the exact same issue. I have determined that all the RAM sticks are functioning correctly but my second RAM slot from the bottom doesn’t seem to work. It’s a brand new machine. Is this a more common issue because I’m seeing this on a variety of different forms... going to schedule a repair from AppleCare but wow! Super annoying!

Brand new 27” iMac 5K and two of my four RAM slots are useless! When RAM is installed in either of the bad slots the machine fails to boot and screen stays dark.

Apple initially thought I bought bad after-market RAM, but after many swaps between the installed RAM and the two 16 GB sticks I bought in they agreed the slots must be bad.

Let’s see how long it takes them to repair or replace. Frustrating!

I also just purchased a 27” 5k 2017 iMac and have isolated the problem to be my 2nd from bottom RAM slot.

* The stock memory reads in slots 1 & 3

* The new memory reads in slots 1, 3 & 4

* The new memory and stock memory reads in slots 1, 3 & 4

But if anything is in slot two the machine will not boot at all.

Very frustrating! Just spent my life savings in this machine and for it to arrive broken is very upsetting!

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Ensure you have seated all RAM sticks properly in their slot, verified the keying matches and visually inspected the metal contacts between the RAM and the motherboard. There should no play in the installed RAM. This generally takes more force than is usually expected. Your system's symptom is typically that of no RAM installed. Check back with more information as it becomes available to you.

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Thanks for your quick response, I also read that the RAM had to be inserted fully. The Mac did not turn on because I had not seated the RAM all the way.

I pressed the RAM firmly into the slot and then again after closing the lever before testing, it worked perfectly.

Glad I could help. It's surprising how hard you have to push to get them memory sticks in. I'm always afraid I'm going to break them.

I have done the above twice, computer still dead, took the two new ram-sticks out, and computer is well again....

I should have the right ram, 2x16, pc4-19200 DDR4-2400 kit, from OWC....

After having talked with owc-chat, they asked me to press Cmd, Option and p and r, and then start the computer, and thát did the trick....

Had same problem. The above solutions did not work for me. BUT ... I did figure out the solution. After taking note of the original Apple RAM locations, remove the Apple RAM and put the new RAM modules into those original locations, then put the old Apple RAM into the previously empty slots. That worked for me. For some reason, the MAC wants Apple RAM in those originally empty slots - probably as a ruse to get you to buy Apple memory instead of less expensive OWC, Crucial or Vengeance RAM. Crucial works fine.

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I had the same issue, mac not booting after RAM upgrade. I put the RAM sticks in the empty slots, but wouldn’t boot up. I took each of the new RAM out one by one and swapping them in the available slots, and figured that my second slot (from the bottom) is not working. I then decided to put the existing RAM in those sockets, to see if it does the same….nope, it booted. So then i added the new RAMs (in the sockets where the original sticks were) and it finally booted up and recognized all of them. Don’t know why it did this, but in the initial configuration it would boot with only one added stick in the top socket.

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Had same problem. The above solution worked for me too. Move the original Apple RAM to the empty slots and then add the new RAM to the slots where the original Apple memory was located.

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I read that it could take 30 seconds or more for the computer to initialize ram if some was added or the sticks rearranged. Did you wait at least 30 seconds after powering on with the new ram added?

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This thread was helpful. I had to try every combination of configurations, i.e. ram chips in different slots, until it worked.

I had 2 - 4GB OEM RAM chips installed in slot 1 and slot 3.

I bought 2 - 8GB OWC RAM chips and it finally worked in this configuration:

4GB/8GB/8GB/4GB

Machine is 27” iMac Retina

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Oh my God! After a weekend of trial and error and lots of online research, John's configuration worked for me!

I had watched the 9to5mac video https://www.youtube.com/watch?v=-YyPmGLH..., on the ease/$ savings of upgrading RAM in a 2017 iMac 27". I purchased the Corsair Vengeance 32GB RAM: http://amzn.to/2sTZtXh the author suggested via Amazon and installed 2x16gb sticks into blank slots 2 and 4 (I had 2x8gb OEM sticks in 1 and 3). The new configuration would bring me to 48gb of total RAM. Only problem was, it didn't work initially and was throwing my 2017 iMac 27 3.4 i5 (18.3) into an endless restart/reboot loop. I tried several re-installs/configuration changes and confirmed all sticks were seated properly but the problem persisted until I found this thread and John's post.

I had 2 -8GB OEM RAM chips installed in Slot 1 and Slot 3

I bought 2-16gb Corsair Vengeance RAM as outlined above and configured them like this:

8gb/16gb/16gb/8gb. IT WORKED!

My machine is 2017 iMac 5K Retina 27 3.4 i5 (18.3)

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Of course, the RAM slot can be DOA / broken.

If you have inserted a RAM stick in slot 4 and 1/2/3 it does not boot, and that stick works in slot 1/2/3 and you have inserted it properly it is perfectly possible.

You can also try resetting the SMC by disconnecting power and waiting 15 seconds and then plug it back in, wait another 5 seconds and turn it on.

And NVRAM / PRAM by turning off the mac and holding CMD+ALT/OPT+R+P and turn it on and hold until you see the progress bar. Please check Startup Disk, Display, and Date & Time settings as they may have been effected by the reset.

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I had the same problem and tried every combo as well. I do believe the problem was it took longer to recognize the new ram and boot up. I just wasn’t giving it enough time. All is working great now with 64 GB ram installed

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How long? 10 min or like an hour?

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In my issue: I bought two sims Hyper with the same specs. except because they needs 1.2 volts. After a test a lot of combinations, iMac only work with the two OEM or with the two HYPER. It seems like OEM and HYPER are not compatibles.

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