Make sure you have the latest BIOS version installed for your model motherboard. See Drivers and Tools tab here:
https://www.asus.com/us/Motherboards/Z170-PRO-GAMING/HelpDesk/If your ram is rated 3000Mhz, use the drop down menu in the BIOS for the ram section and choose XMP. (SAVE your BIOS settings and reboot)
If that doesn't work, manually set the ram to 3000Mhz in the BIOS.
Corsair 500R Case, H110 Hydro, 1200AX PSU, Asus Maximus Hero VI MB, Intel 4770K CPU, Gigabyte GPU GV-N98TWF3OC-6GD, G-Skill Trident 2400MHz 32GB, Crucial M500 960GB SSD, Seagate 6TB HDD x2, Creative SBZ to Denon AVR-4311ci - Infinity Primus 5.1 w/Klipsch Sub XW-300d, HP ZR30w 30" S-IPS LCD, W10 64bit