The Intel Sandybridge Systems are set to show the Overclock only when the CPU is under load (Using Turbo)

If you suspect the system is not Overclocked you can download 2 programs

CPUz and Prime 95 to check

Install CPUz and Run Prime 95 Selecting Stress Testing and one of the top two options

The Speed of the CPU in CPUz should increase as the system CPU is put under full load

If the CPU speed doesnt increase you can re-load the Overclock Profile as detailed in the link below for Core I7 Sytems as the Bios is the same configuration
On the Asus Boards you may need to select Exit and Advanced Mode and then goto Tools