Kenton82 :
Look in your BIOS and enable XMP profile. But remember that ram will show up in CPU-Z as half the frequency (DDR - double data rate)
K.
Kenton is right.
You have to go into the BIOS and tell the ram to run it's XMP profile for 1866. (Also your motherboard has to support 1866 ram speeds)
CPU-Z shows ram running at half frequency because it doesn't Double the Data Rate (DDR) of the ram like task manager and the retailer page do.
Nothing is wrong with what you're seeing.