RAM running @ 2133MHz when board supports 2400MHz

[an Original Name]

MOBO - Asus B250m-A
RAM - Corsair Vengeance 2x4GB @ 2666MHz

Do I have to go into the BIOS, and if I do, what to do... Thanks!
(sorry it's short, I wrote more then 't'was deleted so now I cba to write much)

 

[Dark Lord of Tech]

Go into the BIOS under DRAM settings and select XMP profile for 2400.