Bios : Ram frequency wrong

Hi,

I've recently experienced the following problem :

During a cold boot (like after hours of inactivity), the computer doesn't manage to start correctly, but does the reboot after, like nothing happened.

I've been looking arround a bit and started to read about people having similar problem.

I recently upgraded my RAM from 8gigas to 16gigas. I went on kingstone's website, did the "which ram is done for your computer" and here what I've bought :

DDR3 1866Mhz - CL10 - DIMM - 2x8gigas

At first I didn't experienced the problem, it just poped up from nowhere since 1 week and today I had my first blue screen (too fast to read but something about memory) and computer crash.

So I figured out it was the memory and after further verifications I saw that the BIOS is indicating the wrong RAM frequency, set up to 1600Mhz...

Problem is the zone is greyed out so I can't make any changes in the BIOS (in order to set up the right frequency....)

Can anyone help me to figure out how i can make such modifications in the BIOS ?

Ty for your answers.

Computer . Alienware x51 R2

Windows 10 64-bit

Intel Core i7 CPU @ 3,40GHz

Radeon RX480

16GB RAM