If you went from 2GB to 3 or 4GB of RAM, I'd advise you to "recertify" your OC settings. You obviously have OC"d your E6300 to 2.8GHZ. If it's DIFFERENT memory under an earlier OC regime, you should go through the entire PRIME95 tweaking process -- starting at least with slightly lower settings (FSB/DDR) than you had previously certified as stable.
And since you DID OC, re-evaluate the voltage setting. IF the command-rate is set to "Auto", see if it defaults to 1T, or if it's set to 1T anyway, set it to 2T and reassess.