Use of a Windows Diagnostic Tool on my iMac HD by a Technician

No, a disk controller is the disk's own built-in embedded chip that communicates with the computer. It translates the generic peripheral bus commands the computer uses into disk-specific control and electrical signals to actually operate the disk itself.

I'm a bit late here, but I will try to help clarify a few things.

The tech appeared to have removed the Apple hard drive when they ran the Crystal Disk Info report since the Interface listed in the report is "UASP (Serial ATA)". The "UASP" part is a special USB protocol which indicates the hard drive was connected externally using USB to a Windows' PC.

The hard drive in that Crystal Disk Info report looks healthy although the complete report is not shown. With almost 33K power on hours the hard drive possibly has about 40%-50% life left regarding only the Power On Hours (the report is showing more like 37% worn with 63% remaining), but most hard drives these days rarely make it to 90K Power On Hours even under ideal circumstances....an iMac is far from ideal circumstances. As for someone mentioning the higher failure rate for Seagate hard drives, that was certainly true for many years starting around 2011 and lasting for about seven years, but they appear to be holding up better these days (I have even started using them again).

DriveDx (free trial period) can retrieve the health information of hard drives & SSDs which is the nicest looking & easiest to use macOS app of this type. DriveDx does a good job of analyzing & summarizing the health of a hard drive, but no apps are able to correctly summarize the health of an SSD....an SSD's health must be manually interpreted each time DriveDx notes any changes in an SSD's health information.

I would actually be interested in seeing the complete DriveDx text report for both the internal hard drive and SSD. Post the complete DriveDx text report here using the "Additional Text" icon which looks like a piece of paper on the forum editing toolbar.

I'm also curious about the memory as well since one of the Kernel Panics mentioned the memory changed after some memory was released. This could be due to a software issue (usually third party), or from bad memory. You can create and use a bootable MemTest86 USB stick to perform a longer more thorough memory test than the Apple Diagnostic performs. Make sure to only use the default MemTest86 settings since modified MemTest86 settings will unfortunately cause MemTest86 to freeze on the 2017+ Mac. You can use the downloaded MemTest86 .img file as a source for Etcher (Mac, Windows, Linux) to create the bootable MemTest86 USB stick.

If I read right, you are correct.

In the 27" iMac's including the 2019 model, the matching modules should be installed in DIMM 0 and 1 pairs which I believe are slots 1&3 and 2&4.

Then along came the 2020 model, where the matching modules should be installed in Channel A and B pairs which I believe are slots 1&2 and 3&4.

lifewebb wrote:

I have downloaded and used the DriveDX software. It astonished me by hardly being open for 5 seconds and then delivering its reports. How did it manage that I wonder...

All DriveDx does is use a free open source utility to ask the drive for its health information which consists of very little actual data to transfer.

Perhaps I should run it again in an hour or so.

There is no need unless DriveDx would alert you to a change. Since there are no obvious immediate issues, then the report will be nearly the same.

I have one comment about the DriveDX reports concerning the Temperature measured. It is 17 degrees C right now, before sunrise on the west coast of Mexico. The iMac has a little heat emerging from vents on the back but is otherwise cold to touch. I was perplexed at the high Temp reading of 34 C. I would expect the fan to be operating at that temp but it's not.

The only temperature I'm a bit concerned about is for the Seagate hard drive that reached a Lifetime Max Temperature of 60ºC, but that is probably due to being installed inside of an iMac that runs hotter than most systems. It is still within the manufacturer's safe range, but Seagate drives typically run cooler than most other brands. The 34ºC hard drive temp is actually quite good especially in an iMac.

Yesterday, Jan 17, I finally did a Disk Utility check of the HDD inside Recovery and it came up with a failure on the Data volume. Pictures attached.

This result is leading me to decide to erase and reinstall and see if my problems go away. I was going to do it this morning but have stopped in order to respond to your kind input.

Try running First Aid on the hidden Container. Within Disk Utility click "View" and select "Show All Devices" so that the hidden Container appears on the left pane of Disk Utility. If after several scans the errors remain, then a clean install is the only option to correct them by using a fresh file system.

Important: Wake should be disabled. You might see a substantial improvement so please make the change asap. Leave as is even if no immediate difference is noted.