I was testing some DDR3 SODIMM modules using Memtest86+ on a Lenovo Thinkpad T520. I re-tested a module that I previously marked faulty and it came out fine.
So I wonder if it's possible that the module wasn't properly connected before.
Do these modules have some self-diagnostic facilities that would detect a break in one of the lines or would e.g. a break in a higher address line go undetected until higher memory areas are actually accessed?