This is kid of a rant search fro more information.
We have a client with a Lenovo M5 3100 unit. It boots correctly, but if you try to enter DSA it fails the memory pre-check. It jumps from DIMM 2 or DIMM 4 depending on the replacement board. It is under warranty. We/Lenovo have replaced the Mainboard(Refurbished 3 times, RAM, and CPU(2x). This leads me to believe that refurb boards are not being tested correctly. This is really disheartening. I am normally the champion of Lenovo. However, it is only one issue. We have 100's of systems in theild.