Gigabyte ga-z170x-gaming-g1
2 SAMSUNG 950 PRO M.2 512GB MZ-V5P512BW

I want to config the 2 SAMSUNG 950 PRO M.2 512GB as raid 0
I need to choose between 4kb 8kb 16kb 64kb 128kb for strip block size
what is the difference between all of these sizes and what is the best choise
This ssd raid use for oparation system (win 10 pro) and install and play games

I need to write the 2 ssd 512 totla size
What is the exact size and how can i calculate it
Gigabye wrote 953,875 - is this any 2*512 exact total size?
thank you much