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

In other words, this HDD may be prone to failures - which the ridiculous power on count from Crystal Disks may indicate the reason for - a poor disk controller that powers the disk on and off too often.

Thank you for the input! Just to say that in System Info, under Hardware, a category called 'Controller' says: "This computer doesn’t contain any Controller devices." Is there somewhere else to look for what you are referring to?

I could tell you that I bought two 16GB modules from Amazon MX, thinking that it would make the computer even faster and they were sold under a brand called TimeTec which allegedly were the correct ones for this iMac 2019,1 - 27 inch screen. Compatible with Apple DDR4 2666MHz / 2667MHz for Mid 2020 iMac (20.1 / 20.2) / Mid 2019 iMac (19.1) 27-inch with Retina 5.

On 14 Jan, due to the reference to 'memory' in some crash Reports, I removed the oldest and original memory that came with the computer at the end of 2019, which may have been manufactured in 2018 for all I know, and perhaps one of them is malfunctioning. I discovered that the 16GB modules had been made by the same manufacturer that Apple had used for its 4GB modules - SKhynix.

It was a test of my own devising. Now the RAM consists of two 16GB blades which are correctly installed as the first two modules at the bottom of the tray. However, the day after doing this change, the computer again crashed and its report said 'Possible memory corruption'! So, I am no further on with whether the physical RAM is causing trouble.

Thank you so much HWTech for all your advice and guidance. I have not done the MemTest86 procedure as I didn't have the bandwidth to take in what I was supposed to do.

I have been overtaken by attempting to a) Boot into Recovery in order to run Disk Utility in it again and see if was possible to check the Container level of the hard drive and 2) by attempting to over-write OS Sonoma with Sequoia as System Settings keeps urging me to do.

Now the iMac will not boot into Recovery mode. I tried twice. It just comes to the normal interface. This may be caused by a fault in my magic keyboard (it had an accident with water about a week ago) or something else. Only using a different keyboard could clarify the situation - but none is to hand, alas.

Yesterday I did all my backing up manually to two external drives and then decided to answer Apple's call to update the OS to Sequoia. I thought this might erase any System level problem at the root of the many crashes and restarts phenomenon.

However, the process aborted about half way through, see image below, + Text Edit crashed, so I could not keep a record of what the detailed reason was for it aborting & System Settings crashed, so I shut down the computer for a long break and went to the beach!

I can do no more on my own (am too frazzled with investigating it!) and will take it to another English-speaking technician with very good reviews on Google when his schedule permits. Or to the local equivalent of Apple Store but no English spoken there and not very accessible for a semi-disabled person like me trying to move a very heavy iMac in its box from the parking lot underneath...

My plan is to have a technician erase the drive, without dismantling the iMac and putting the Fusion drive into some external setup. Install OS Sequoia ONLY from Apple's servers, not from some copy sitting on one of his external drives. He should use my User name so the iMac stops behaving like it is a new computer so far as my data is concerned. And the formatting nomenclature should return to the standard one of 'Macintosh HD'.

Only after this attempted rectification has been done, and has failed to cure my problems, will I move to believing that the only solution is to replace the Fusion Drive with an SSD. I am at the end of my tether as you can see!

All thanks to everyone else who has chimed in with valuable information and suggestions. So much appreciated having the chance to discuss my situation. :-)

Thank you den.thed. I appreciate your advice - However, the crashes and restarts are not happening on being woken up. Or perhaps only once did that happen. Vast majority of them happen after 1 or 2 days of normal operation, at a random time of day. My setting for 'Energy' is set as your screenshot shows, although I also have it set to 'Wake for network access' and I can certainly see evidence of things happening during the night that show up in some sections of System Info.

Re. Etrecheck - I am amused to inform you that I did try that and it immediately crashed! Twice. Would not do its work. Nothing I could do! I think I have a report for that one.

I have just done a second Etrecheck diagnostic this morning and here it is. Think there is something wrong with the RAM modules but without knowing which one or ones, what to be done?! Maybe take out the ones I bought from OWC and leave the original Apple ones in to see if the problems disappear? And if the RAM thing is not connected with the crashes and restarts, then I have this other hardware problem with the hard drive.

One thing I wanted to do was to ask Disk Utility to do a check of the situation but do not know which part of the tree to tell it to check - 'Container disk 2' which is just below Fusion Drive? Or the 'volume'? And advice on that would be welcome.

Thank you for this clarification and sorry for delay in responding.

Do you know of a Mac diagnostic tool which could produce a similar report to the Crystal Disk Info one?

varjak paw wrote:

The only way, unless I'm missing something, would be if the tech connected the hard drive to a Windows system which if the iMac was disassembled was probably what was done. As you say, CrystalDiskInfo is a Windows-only utility. Without knowing what else the tech might have done with the drive, I can't say that it's impossible that he/she caused a problem with the drive, but I don't think CrystalDiskInfo itself would have done that.

Thanks, but how could a Windows software be applied to an Apple HD? Did he erase the whole thing - nothing Apple left on it and then format it to be used by Windows in order to use the Windows software? Then erase again and install OS Sonoma from one of his hard drives? Because it definitely did not come from Apple directly as it was not up to date. I have checked Sonoma version Release dates and other software like Image Capture. I got an old version of Image Capture which does not work properly! And the latest version of Sonoma was not installed, I had to download it myself.

I think that is what must have been done. Since there are Mac compatible softwares to do the same diagnostic, I am just astonished that the HD has been 'fiddled' with in this way and it has generated mistrust about a change being made to the HD and some kind of 'residue' of formatting being left behind, messing with the operating system and with apps. Chrome is not behaving normally now either, for instance.