Bios and OS detects 4 gigs of ram instead of 16 gigs (2*8 installed)

[prgrmmr.aben]

Hi,
I have a new configured desktop pc, (you know the open market risks)
anyway, the issue is that neither bios, nor the operating system detects 16 gigs of Ram, they only show 4! here is my spec:

Intel i7-4790k CPU 4.00GHz
Installed memory 4.00 (3.88 Gb used)
OS: Windows 10 Proffessional
motherboard: Z97-PRO GAMER V 0402
(8Gigs * 2 ) of RAM HyperX DDR3 1866 CL9

I am not advance in hardware, so please bear with me, I came across several discussions but all with different specs and the solutions many times differs (changing Ram voltage in bios, changing Ram location, upgrading bios...)
I don't really want to start messing unless I'm sure any configuration change would not be risky. That's why I'm here.
Thank's in advance.

 

[popatim]

Run cpu-z and post screenshots of the memory and spd tabs please.
With memory prices being so high, I can see counterfeiters might take advantage of people.