i am not very experienced with computer builds but one thing i do now if youre not going to over clock your cpu you dont need the i7 5820k
The K mean the cpu has an uncloked multipiler, meaniing you can overclock the cpu in the bios by increasing cpu multipiler.
so you can swich that to another but do some more research regarding that.
also if you are going to switch the hdd in the future maybe you shouldnt buy so much storage and if you need more buy a new hdd. but you may need it i dont know what you will do with the rig. but it sounds kind of overkill with 4x 2 Tb hdd.