iMac 5k shuts down randomly

Cocktail should be uninstalled, it was useful about 10-15 years ago, however Mac OS has progressed greatly since then making Cocktail worthless.

I don't suspect your OWC RAM however it may be wise to run the computer with only the original RAM that shipped with it for about a week and if continues with the Kernel Panics then you know it was not caused by the OWC RAM.

I suspect 2 things, first is the hard disk portion of your Fusion Drive may be failing, run DriveDX on the HD not the Fusion Drive and if any errors appear that means the HD is failing.

The second thing I suspect is your power supply may be failing. If everything else checks out okay that means its likely the power supply and you need to take the computer to your local Apple Authorized Service Provider to have it serviced.

When did you upgrade/add RAM and what vendor did you use..?

I would try reseating all of the RAM modules first. Then if that doesn't help, I would test it with pairs. First the factory modules and then the aftermarket modules.

Have you installed and run any "cleaning", "optimizing", "speed-up", anti-virus or VPN apps on your Mac?

Ross Novie1 wrote:

I purchased 2x16 gig RAM modules from Macsales (one world computing) shortly after buying the computer in 2019. I'll try that out. Thank you!

You’re welcome.

One module could be loose or have a bad connection. They can also fail, but that would likely show up at startup.