i'm pretty confident there are other options for dee. Your ram is running pretty fast & stressing the NB. You can give the cpu up to 1.40v actual, unless you're already doing that. you're ram could take up to 2.1vdimm which may aide in stability. Good luck but i doubt it is a bunk chip, seriously.

An easy way to tell is to see how "hot" it runs on air at a particular Vcore & speed - depending on your cooling.