Congratulations on your Diagnosis and fix. 
I can confirm that the electrical connection between Dimms and their Sockets can often deteriorate over time, especially with the heat cycling of running a system that is running hot, and then cooling down when switched off.
If more players would occasionally run a memory checker/ stress test like MemTest86, there might be far less people blaming MSFS for their computer issues.
Just as some obsess over what heat sink compound they use when building a PC, everyone might consider the DIMM contact issues. There are products like
That both de-oxidize the connection, as well as protect it from future oxidation.
(also great for cleaning the contacts on your Credit Card chip gold contacts!! )