Issue with ram is seen with code 2000-0122

I have my laptop of Inspiron 3576, with 8GB RAM during purchase. A few month after purchase I added another 8GB RAM that gives total of 16GB RAM, which worked well for a couple of months and yesterday my laptop turned off automatically and failed to load windows after that. and I run Pre-boot System Diagnosis that gives me the error code of 2000-0122. I run the Pre-boot System Diagnosis using only both RAM one by one and I found that the error was given by the RAM that comes with the Laptop. And when I try to boot up with the faulty RAM, the windows is opened but it showed that 3.85GB was for Hardware reserve with the 8GB RAM installed. And the next time when I tried to run windows with the both RAM, the windows opened and i saw that the Hardware reserve was 11.6GB with the 16GB installed RAM in both slot. Q. Why this might have been happened? Q. What should I do? Q. Why and how this Issue happened?