After I upgraded my iMac to Ventura, I received a kernel panic

I understand what you are saying, but that doesn't necessarily mean anything.

You should definitely check with Crucial support to verify if those memory modules are compatible with your iMac. It doesn't make sense to do anything else until you get confirmation from Crucial. You should also verify all four modules have the same part number as well. If they have different part numbers, then you will need to confirm with Crucial if those two parts are compatible. If they were purchased as part of an official Crucial Kit, then they should be identical, but if they were purchased individually the modules may have different part numbers.

Memory compatibility is so crazy these days, that even buying the same part number from the same vendor at the same time can still cause compatibility issues when mixing memory if they were not all manufactured on the same day & on the same line. That is why Crucial and other memory vendors tend to sell memory in "kit" form. Like I said, memory is not simple these days. I can no longer keep up with all the changes and will ask Crucial or even the OEM of the device to confirm if the memory configuration I'm planning is acceptable before making a memory purchase. I never used to do that years ago.

This is also why most contributors on these forums will only recommend memory from Crucial or OWC. Even then the memory purchased must be the specific part number that the memory vendor recommends for that specific computer. Crucial & OWC make it very easy to identify the correct compatible parts. It is a bit more difficult & risky to then buy the RAM from a third party unless the third party vendor are very precise in providing actual Crucial part numbers to confirm compatibility -- most official authorized Crucial resellers do this, but other unauthorized resellers may not.

I'm glad you were able to confirm the bad module.

FYI, sometimes if memory is purchased as a kit, Crucial may want to exchange both (or all) modules instead of a single module. Mostly because of possible compatibility issues from using mixed memory (even from different manufacturing runs). Probably depends on the computer as well.

We've never had any problems getting a warranty exchange from Crucial for the few times we had to exchange something (a few times out of several thousands of items purchased) over 20 years.

If you boot into safe mode, does it work?

How to use safe mode on your Mac - Apple Support

If so, you have a third-party system modification that is incompatible.

P. Phillips wrote:

After Market RAM at play ?

You beat me to it!

The user may consider Re-Enabling SIP

" System Integrity Protection disabled - System Integrity Protection is disabled. "

After Market RAM at play ?

That is difficult to do 😀.

Let s hope it is RAM and not LogicBoard as that too may present similarly