You can use DDR4 3000. however, to use it at 3000, the system will need to change BCLK up to 125 which will cause problems elsewhere, but it is possible.
you can always turn the wick down a little and run the RAM at 2666 Mhz, which I think is the fastest that will run on BCLK 100, and I'm pretty sure it will work at 2400Mhz, so I'd keep it..
http://www.anandtech.com/show/8426/the-intel-haswell-e-cpu-review-core-i7-5960x-i7-5930k-i7-5820k-tested/3