Happened with me. Turn on TurboCore. If it does not work, turn on Load Line Calibration (LLC) one increment up. If that doesn't work, do 2 increments. If that won't work, do 3. If that doesn't work...turn both on. For me, turning TurboCore on, and increasing the max Ghz helped. I OC'd my 6300 to 4.3Ghz @1.404 and have TurboCore on set to 4.4GHz max. Also, is your 6300 OC'd? If yes, what GHz and voltage you getting? Did you play with the multiplier or FSB or both?