A couple of details to fill in before the RAM specialist get here:
1. I'm guessing that your BIOS shows all 16GB RAM being present?
2. Have you tried to play BF3 with just the 8GB of new
At some point someone will ask you to check your RAM using MemTest86+, so you may as well run it. Usually, 6 full passes are recommended and for 16GB RAM it will probably be an overnight job. You can download MemTest86+ here
- burn it to a bootable CD/DVD/USB then boot from that, and run it.
You might also want to follow this tutorial for capturing more advanced dump information, and then posting your jcgriff file here.