[weblacky]

The usual questions, what are the model numbers of the memory. Are they all the same manufacturer or they are different third-party Memory manufactures. What’s the layout of the manufacturer placement?

Since they are installed in pairs I would probably argue that you have two different types (manufacturers) of memory occupying the same bank. Re-order your modules so that there are same manufacturer in pairs. If you don’t have an equal number of modules part numbers to have them in same pairs then last Man standing is probably your issue.