1866 Memory speed & Gigabyte 990fxa-UD3

Hey all,

I just put together a system and need a little help with the memory.

I have an AMD PhenomII 980 @3.7ghz
with a Gigabyte 990fxa-UD3 mobo
And 8GB(2x4gb) of Corsair Vengeance DDR3 1866 memory

I can get it to run at 1600, but need to know what to tweek to get it up to 1866. Where do I start? Im not sure what timings they should be set to either. kind of a newb at high end stuff. Always just popped in the chips and forgot about em. Now I need some learnin'!

Thanks for the help, in advance!