My son's runs at 3.78 GHz at 55-58 core temps. Have you tried lowering Vcore ?
Follow the guide here:http://vip.asus.com/forum/view.aspx?id=20081220191040237&board_id=1&model=P6T+Deluxe&page=1&SLanguage=en-us
They recently redid the tables for the 950 and 960 (was 920/930) wish they wuda kept the old tables, wuda made it easier for ya. But the voltage optimization section section still applies.