Your ram is already running at 1333. Most bios and cpuz report the ram speed as half what it actually is. It won't harm it to run it faster. Use the memory option on cpuz to confirm the speed. 667x2=1333. I've got 2 sticks of 1066 ddr3 with 2 sticks of 1600 ddr3 running at 1600 with the cpu overclocked. Cpuz reports it as 798; some variance is normal.