What make and model of motherboard are you using? Also, even if you set your memory to that speed (in the BIOS), you may make the system unstable and unusable as a result. When you use memory that is rated for higher speeds than the standard (1333), you essentially are overclocking your memory to take advantage of that higher speed rating. Overclocking memory actually provides less of a performance increase than many users expect.
Please clarify the info regarding your motherboard and I am sure we can help.