LieutenantLysol :
Upgrading to a Intel Core i7 6700k supporting DDR4-1866/2133 and motherboard supporting DDR4 2400/ 2133. What's the max speed of dram I can run?
Its best to check the MB QVL list and select a kit of RAM at the frequency you desire that have been tested in conjunction with your MB.
OC RAM are not guaranteed to work without Bios intervention. If you have no Bios experience with setting XMP profiles or adjusting Primary Timings then choose a kit at 2133MHz. There is very little difference in gaming performance.