iMac 2019 27" possible memory corruption kernel panic

sleepyfran

macrumors newbie
Original poster
Sep 11, 2019
3
0
Madrid, Spain
I bought my iMac back in May with 8 GB of RAM and upgraded to 40 GB adding 32 GB of Crucial RAM (to be precise, this exact kit which I've seen recommended a couple of times on the forum). Worked perfectly without any issues, macOS detected all the RAM with the right speed. But 12 days ago I was just using Safari and suddenly it turned off and showed me the kernel panic screen. When I restarted I got the logs saying that I had a "possible memory corruption" (I can post the exact logs later, I'm not with my computer right now) with an unknown BSD process name in the current thread and no weird kexts loaded (all of them were com.apple.something). I ran the macOS memory test and another RAM test I found on the internet and none of them yielded any error, so I didn't pay much attention since it was the first time that happened.

Forward to a couple of days ago, I was watching the Apple live stream and the computer just started freezing for a couple of seconds (not even taking IO input) and coming back only to freeze again, so I had to force shut it down and when it booted up again it showed me the kernel panic screen, restarted and saw the "possible memory corruption" message again.

Now I know that I can remove the Crucial modules and try if it happens, but I need the extra RAM since 8 GB is not enough for my usage and since it happened with lots of days of difference it's a difficult test to try. Is there any other way to test what might be wrong? Has anyone had trouble with Crucial modules? All the posts I've seen here with similar messages were of faulty OMV modules.

Thanks!
 

sleepyfran

macrumors newbie
Original poster
Sep 11, 2019
3
0
Madrid, Spain
A little bit of an update: yesterday it got worse and I actually got two kernel panics in half an hour, I ran Rember tests again and this time it showed errors in the first run:

FAILURE! Data mismatch at local address 0x0000000908bd4580
Actual Data: 0x0000000900bd4580


So well, today I decided to remove the RAM that came with the iMac and try again: the error in the tests are gone. So of course I need to check more days to really see if it's fixed but so far no kernel panics and the tests pass. I also noticed that the Memory section in the About this Mac now shows that it's running at 2667MHz when it previously showed 2666MHz, so maybe that can be what was happening before.

Edit 11th of October: yep, I can confirm that was indeed the issue. Hadn't have any kernel panics since I removed the RAM that came with the iMac.
 
Last edited:

Fishrrman

macrumors P6
Feb 20, 2009
17,200
5,547
If it runs just fine with the 32gb of Crucial RAM installed, I'd just use it that way.

Another avenue to try:
Put the Crucial RAM where the ORIGINAL factory-installed RAM was.
Then put the factory RAM in the free slots.

Perhaps "swapping the DIMMs around" might produce the working combination.
Of course, if you try this, you'd better keep WRITTEN NOTES so you don't go around in circles!
 
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sleepyfran

macrumors newbie
Original poster
Sep 11, 2019
3
0
Madrid, Spain
If it runs just fine with the 32gb of Crucial RAM installed, I'd just use it that way.

Another avenue to try:
Put the Crucial RAM where the ORIGINAL factory-installed RAM was.
Then put the factory RAM in the free slots.

Perhaps "swapping the DIMMs around" might produce the working combination.
Of course, if you try this, you'd better keep WRITTEN NOTES so you don't go around in circles!
Hmm, that definitely looks interesting! I'll keep using just the Crucial RAM for a couple of weeks and see if the problem is gone and then I'll try swapping the RAM around and see if it makes any difference. Thanks! :D