The max temperature recommended by AMD is 62c, so you'r just under the threshold.http://products.amd.com/en-us/DesktopCPUDetail.aspx?id=617
Try lowering the voltage as low as it can go before it becomes unstable.
Try and ensure case airflow is sufficient, dont want hot air cylcling back through the cooler.
Other than that I think you will either have to back off the overclock or upgrade your cooling. From a Noctua Nh-D14, the only real upgrade you could make would be custom water-cooling.