You forgot to state the motherboard. If you are working with a H or B 100/200 series chipset then there's no point in getting a K suffix processor part. Likewise if you're on an 100 series chipset, you're going to need the Skylake processor to perform a BIOS update and then be able to drop in a Kabylake processor part.
Mind you, what are you currently working with? Mind sharing the full system's specs?