It may come as shock to you, but I did search (as I usually do before I reply) though I didn't have to.
http://www.gskill.com/en/product/f4-3000c15q-16grbb
http://www.gskill.com/en/product/f4-3000c15q-16grbb
Quote
Tested Speed 3000MHzTested isn't default.
...
SPD Speed 2133MHz