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*16GB

After the upgrade the mac 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 verifyed that the.RAN is compatable and should work with my iMac.

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

Answered! View the answer I have this problem too

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Have you tried to use the chips 1 by 1 to isolate the issue? It could be a bad chip.

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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.

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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.

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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....

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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....

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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 16*2 or single module .

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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

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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 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!

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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 16GB sticks I bought bought they agreed the slots must be bad. Let’s see how long it takes them to repair or replace. Frustrating.

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