MartA n,
I would suspect that these modules will run OK on the X99 platform but many people on the Z170 platform have found out that modules for the X99 platform are troublesome on the Z170 platform as factory specs are different between the two platforms. 3200MHZ modules that Arne is suggesting work very well on the X99.
Keep in mind that every CPU is a little different and what works on one may not work on another. With the memory controller on the CPU it is a biggest variable on these platforms