Hi there, you need to go into the BIOS to get it to run at the rated speed. When you install the ram, the motherboard will just default it to safe settings (1066MHz @1.5V). You need to tell it that the RAM can run at 1600MHz @1.65V (CL9).
You can do this by either enabling the XMP memory profile within the BIOS or inputting the rated settings from the frequency, timings and DRAM voltage manually (refer to your motherboard manual on how to get to these BIOS options).