I had nothing but problems after installing Mac OS Catalina on a brand-new maxed out 2019 iMac 27" 5K. The machine, as I write this, is barely 2-weeks old. As you know, Apple charges a premium price for RAM updates. So I did what many do, I bought this machine with 8Gb and upgraded it to 128Gb when it arrived using a RAM upgrade kit from OWC.
The KPs and reboots were endless. Apple's built-in hardware diagnostics said everything was working correctly. So, I decided to take the iMac back to its delivered OS, Mojave. But with Mojave, I started experiencing KPs as well. Now, I'm beginning to suspect a hardware issue and reached out to OWC tech support. Here's what OWC said after I contacted them:
"Occasionally in the manufacturing process, a module may get splashed with a manufacturing solution that can cause difficulties mounting once installed into the customer's computer. One of the most common ways that this occurs is that the system will be able to boot up fine and the modules will pass basic testing, but you'll get intermittent crashing - it will attempt to utilize a section of the module that is being obscured and this will cause the sudden crash."
The tech support specialist provided instructions on how to clean the RAM and run deeper memory testing using Rember after reinstalling it. The OWC RAM caused a kernel panic every time I tried to run Rember. It would get to different points in the process and fail every time. Keep in mind, this RAM passed Apple's internal hardware testing.
I removed the OWC RAM and reinstalled the Apple supplied 8Gb RAM and ran Rember again. This time the machine passed all deep hardware testing and has been stable since. The machine is still running Mojave and the bad RAM is on the way back to OWC for replacement. I haven't dared to upgrade to Catalina again, but perhaps I shall after the next one or two point releases. Hope this is helpful.
The KPs and reboots were endless. Apple's built-in hardware diagnostics said everything was working correctly. So, I decided to take the iMac back to its delivered OS, Mojave. But with Mojave, I started experiencing KPs as well. Now, I'm beginning to suspect a hardware issue and reached out to OWC tech support. Here's what OWC said after I contacted them:
"Occasionally in the manufacturing process, a module may get splashed with a manufacturing solution that can cause difficulties mounting once installed into the customer's computer. One of the most common ways that this occurs is that the system will be able to boot up fine and the modules will pass basic testing, but you'll get intermittent crashing - it will attempt to utilize a section of the module that is being obscured and this will cause the sudden crash."
The tech support specialist provided instructions on how to clean the RAM and run deeper memory testing using Rember after reinstalling it. The OWC RAM caused a kernel panic every time I tried to run Rember. It would get to different points in the process and fail every time. Keep in mind, this RAM passed Apple's internal hardware testing.
I removed the OWC RAM and reinstalled the Apple supplied 8Gb RAM and ran Rember again. This time the machine passed all deep hardware testing and has been stable since. The machine is still running Mojave and the bad RAM is on the way back to OWC for replacement. I haven't dared to upgrade to Catalina again, but perhaps I shall after the next one or two point releases. Hope this is helpful.
