iMac CPU Kernel Panic - computer shuts down/restarts in sleep mode and randomly.

The fact that memory is aftermarket i.e. not original makes it a likely cause of the KP. The fact it crashes in Safe Mode supports that suspicion.

Macs are completely intolerant of RAM that does not meet its stringent requirements. Remove the aftermarket memory and test. If the KPs subside then it is very likely you found the cause.

At your option you can also run Apple Diagnostics: Use Apple Diagnostics to test your Mac - Apple Support. Run the extended tests. If it identifies a memory problem, you positively confirmed it exists. On the other hand, it may pass those tests, in which case you should consider AD inconclusive. Why? The reason is that it is literally impossible to test memory for specification compliance (meaning, evaluating its performance throughout the full range of its speed, temperature, voltage) using the system on which it is installed.

Assuming you conclude memory is the cause replace it with RAM obtained from a vendor known to support Macs, and there is only one remaining: OWC / MacSales. Crucial (for example) exited that market a while ago.

Short of taking it into a repair tech and opening it up to change out the memory...

You can do that on your own: Install memory in an iMac - Apple Support. It's easy.

>> I've removed all the extra software that was installed when I bought it

you need to boot into RECOVERY> DISK UTILITY and Erase the internal drives

RESET the Fusion (if it has SSD/HDD fused together)

and reinstall macOS from a fresh installer (I prefer thumbdrive macOS installer, Remote will take a long time)

2019 will support Mojave through Sequoia

2017 stops at Ventura (it won't install Sequoia)

eBay is always a risk, but if you paid for a working machine file a claim if you didn't wait too long

easily pull the RAM (google that from 27" 2019 iMac)

lay the RAM out, take a photo of the information side, and post that pic

the RAM on 2019 has specific order of installation

install matched pairs in slots 1 and 3

and 2 and 4

your System Report screenshot looks in correct order

BUT YOU APPEAR TO HAVE 2017 spec RAM installed (clocking at 2400 MKz instead of 2666)

it should not be causing issues in 2019 hardware -- it just runs at the slower speed

reseating the RAM may solve the issue if you are lucky

likewise -- Erase and reinstalling macOS (if you are lucky)

these are great machines -- I would check About this Mac and verify 2019 model (not 2017) -- I hope you can get it back on track...

96GB 2400 MhZ DDR4

I should have noticed that earlier. That speed is not correct for that model iMac. As Install memory in an iMac - Apple Support explains 2400MHz DDR4 SDRAM is incorrect. Replace it. Or, return the Mac to the seller for a refund under eBay's policies.

Unlike PCs we must use correct memory. PCs can alter the memory bus speed leaving the user none the wiser. With Macs, faster is not correct. Slower is not correct. Only correct is correct.

bleedingrose19,

the only real test of RAM is under load

I doubt if you need to buy all new ram

my best advice is to remove the RAM and take a photo of the group, info lable up

and post it -- to give an idea of the manufacturer

include a screenshot of About this Mac to confirm 2019 year

I suspect at least 2019 because 2017 only supports 64gb

I am pretty sure only 64 would show up in 2017 profiler with 96 installed

+++++

to troubleshoot the RAM cards:

reinstall one matched set in slots 1&3 and test

if those are trouble free

swap them with the other matched set in 1&3 slots and test

if those are trouble free

then the issue could be bad 2&4 slots

or

conflicts between ram manufacturers

bleedingrose19 wrote:

THANK YOU! I had a sneaking suspicion that was the issue, I'll try running the diagnostics to check memory specifically.

I would try removing just the 32GB modules (they will be in alternating slots). There is a slim possibility that the two 16GB modules could be original Apple OEM modules and the slower 32GB modules are affecting the clock speed of the 16GB modules. Worth a shot anyway.

Or return the iMac for a full refund (depends on how the eBay listing was advertised of course).

John Galt wrote:

... Unless it's a legitimate Apple Authorized repair facility, they will not know what they're doing, and you are likely to be left in a much worse situation.

You also need to consider the fact 96 GB exceeds the specified maximum memory configuration for that Mac. An AASP should refuse to install that much, justifiably citing Apple's specifications. Of course that doesn't mean you cannot install more, and plenty of people do, you just have to be mindful of the unexpected.

OWC stands behind their products and would not sell it unless they knew were confident it would work. Lifetime guarantee too.

If you're going to go that far why not spend the additional $300 and install 128 GB. I still use Macs with hard disks smaller than that.

these people depend on the credibility Level 10 carries, so it's important to be clear (if you were citing Apple memory specs why not qualify that in your comment?)

I did:

You also need to consider the fact 96 GB exceeds the specified maximum memory ...

... and

You can do that on your own: Install memory in an iMac - Apple Support.

... and the fact that Apple is 100% certain to remove any nonconforming memory, and they might just forget to return it to you. Given todays replacement cost, that would be bad.

Apple's specifications for that model iMac are here: iMac (Retina 5K, 27-inch, 2017) - Technical Specifications - Apple Support

I have found a new respect for you this thread, Mr. John

No problem. I appreciate your kind words, as well as the responsibility decades of Mac experience implies. I don't take these concerns lightly.

You do not have to take that Mac anywhere to replace its memory, and I strongly advise against it. Unless it's a legitimate Apple Authorized repair facility, they will not know what they're doing, and you are likely to be left in a much worse situation.

I wouldn't even bother running Apple Diagnostics. The incorrect memory is a smoking gun in this case. It eliminates all doubt. That Mac will be crashing all the time.

Consider contacting the seller and having them pay for the correct memory. 96 GB is going to be expensive, especially these days. Memory prices have become insane. $869.36 to be precise. Yikes.

>> the fact 96 GB exceeds the specified maximum memory configuration for that Mac

crikey…on the info this thread

27” 5k 2019 iMac indeed supports 128gb (4x32gb)

system profiler is reporting the sodimms 96gb or did you miss that

i have that installed on my 2019 iMac 5k (a 128gb ram kit from Owc macsales) look it up yourself

runs Mojave and sequoia great…

whatever you say...

I know what works and 128gb works, according to macsales OWC (the vendor you recommended for buying all new RAM)

these people depend on the credibility Level 10 carries, so it's important to be clear (if you were citing Apple memory specs why not qualify that in your comment?)

I have found a new respect for you this thread, Mr. John

27” 5k 2019 iMac indeed supports 128gb (4x32gb)

Not according to Apple. Contact Apple and tell them they're wrong.