The first things I'd look at are whether you are monitoring the core temp or the socket temp and also if there is adequate airflow in the case. As far as the monitoring, I've seen a ton of people accidentally mix up the socket and core, the latter of which is the only one you'd really need to be concerned with. As far as the airflow, I would double check that as well to ensure that there is sufficient flow within the case to clear out any heat buildup.
Also, when you say you applied more thermal paste did you carefully clean the first application off before adding more?