Just assembled GIGABYTE GA-Z170X-UD5 with i7 6700k and 4 8 gb modules of ripjaws 2100 DDR4 memory- have been able to sucessfully boot and install Win 10 and no reboots so far-was able to boot with 2 and 4 modules both - memory is 15-15-15-35 but bios is timed to 15-15-15-36 . Thought I would enable xmp and that would fix it- but xmp is not available in bios! - not greyed out - just not there! Bios is f5 ( the most recent is f6 , but is a beta) - I am not an overclocker- but need a stable board - any idea what I can do to get xmp available??