How do I activate second ram?

[spearow.hawk]

So my pc recognizes that i have 2 ram but it only uses 1.
16,0GB (7,99GB usable)
mobo : gigabyte ga-p55-ud3l
ram: 2x kingston hyperx 8GB 1600

 

[alexoiu]

Try clearing the CMOS (unplug the power cord and remove the CMOS battery for a minute).