overclock processor

           Hello I have an Area 51 ALX running Windows 7 Ultimate 64 it has an Intel i7 975 CPU at 3.33 GHZ Back when I purchased this machine, I believed I purchased the processor overclocked. But looking at the specs it appears the CPU is at the base settings. Where do I go into the Bios to see if it is overclocked and if it Is't how would I do it, and is it safe.

                                                                                         Thank you for your help,