BadActor :
Native is the value the RAM runs at without XMP enabled or overclocking. As you have seen, most DDR4 runs natively at 2133 and higher speeds require XMP or overclocking. A very few run at the 2400 speed. As long as your motherboard supports it, I would use DDR4 3000-3200. It has better performance while not paying a huge price premium. GSkill V series are my favorites for Skylake builds.
http://www.newegg.com/Product/Product.aspx?Item=N82E16820231939&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-PCPartPicker,%20LLC-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID=
Using a Gigabyte GA-Z170MX Gaming 5 motherboard (overclockable) with an unlocked i5 processor, which is better: Higher MHz or higher GB?
With an i5 6600K overclocked to 4.4 GHz, what CPU cooler should we use?
Thank you for your help!