You'll need to update your BIOS version to at least 3016 since that version is the oldest that supports Kaby Lake CPUs,
source: https://www.asus.com/Motherboards/Z170-PRO-GAMING/HelpDesk_CPU/
Though, the latest BIOS version for your MoBo is 3610,
link: https://www.asus.com/Motherboards/Z170-PRO-GAMING/HelpDesk_BIOS/