ram bug or what?

why does bios show ram frequency at 1600 when i have 1866 installed, how to fix that?


Processor: AMD FX-8320
Motherboard: 990FXA-GD65V2
Memory: G Skill RipjawsX F3-14900CL8-4GBXM   4 Go X2
Video Card: Radeon HD 6970 XOC PCIE 2GB GDDR5
Bios version: K5
OS...