I'd suggest running a memtest.
Memtest86+ - Advanced Memory Diagnostic Tool
Download the ISO, burn it to a disc, and boot off of it. Let it run for a minimum of 4 hours (the longer the better). If you get any errors at all then you'll want to test each stick one at a time and find out which one is the bad stick.
Memtest86+ - Advanced Memory Diagnostic Tool
Download the ISO, burn it to a disc, and boot off of it. Let it run for a minimum of 4 hours (the longer the better). If you get any errors at all then you'll want to test each stick one at a time and find out which one is the bad stick.