Laptop showing 2 of 4 slots used, only has 2 slots?

[Guest]

My laptop is a Gigabyte P55G laptop with an i7-6700HQ, 16gb of DDR4 2133, and a GTX 960m. I've looked around a lot and this laptop only has 2 SODIMM slots however in task manager it says "2 of 4 slots used". everything else is correct including RAM size type and quantity.

Also this is the second of this model I have had after the last one got taken in for something else. There's probably a simple explanation for this, I'm just not sure what that is.

 

[Illumynization]

Laptop motherboards can have two visible slots from the bottom of the laptop and two more on the other side of the motherboard. This means to use the other two slots you would have to take apart the laptop completely to install more RAM.