Question Ram doesn't working at their speed

[Nikos S]

Hello,
So i had 2x4gb 2666mhz ram and they were working fine at their supposed speed. Yesterday i bought another kit of ram so i would have 4x4gb, but i turned on my pc the ram speed was dropped at 2133mhz.When i open bios and i putted on 2666mhz my pc started to turn on and off continuously until i turn it off with the button. I have tried to do it with the docp/xmp so it would donit automatically but it did the same thing. Also i dont think the new ram has a problem because i tried to open my pc with only new 2 amd they worked fine at 2666mhz.It only does that when they are all 4 together. Can anyone please help

 

[Calvin7]

Use of multiple kits of memory have no guarantee to be compatible together.

 

[Nikos S]

Use of multiple kits of memory have no guarantee to be compatible together.

And that means my ram are not compatible?
I have have even tried to put an old stick and a new one and they worked fine at 2666mhz it only cause the problem when they are all 4