https://www.memtest86.com/blacklist-ram-badram-badmemorylist...
The most expensive memory failure I had was of this sort, and frustratingly came from accidentally unplugging the wrong computer.
After this I did buy some used memory from a recycling center that had the sorts of problems you described and was able to employ them by masking off the bad regions.
Errors may be caused by bad seating/contact in the slots or failing memory controllers (generally on the CPU nowadays) but if you have bad sticks they're generally done for.
https://github.com/prsyahmi/BadMemory
I've used it for many years. It only fixes physical hardware faults, not timing errors. For example if a RAM cell is damaged by radiation, not if you're overclocking your RAM.