SSD drive transfer rates!

my new i7 7820x - 32Gb blazingly fast machine is almost finished ,
compared to my good old i7 2600k 16Gb its a monster/beast. no OC yet(i doubt i would need OC for a while).
super quiet.
trying with win10...

here comes the annoying part:

win10
i have been trying to copy my sample library (3TB+) from sata6 HDD to two new 2TB SSD samsung evo 860.
one at a time tho!
its starting off with 200Mb/s then, dropping to 28-50Mb/s range....
none available windows 10 solution is really a help.

changed allocation unit size to 16k seems like i have steady_enough
80Mb/s - 120Mb/s transfer rate, from SATA6 HDD to SSD.

with regular allocation unit size of 4k, file transfers with in the same SSD was very slow too.
i havent checked yet with new 16k

any serious solution to this, or should i roll back to win7

WOOOOOOO  :-\
1TB samsung 860 SSD windows10 boot drive decided to have fun,
drive lost everything.... have to reinstall everything from scratch now 
i didnt even get time to make an image copy  ;D ;D
SSD is just fine tho... whatever happened win 10 couldn't prepare it!
i was doing some BIOS setting for cubase!
may be i messed  with something  :

I also use SS Hybrid Drives. They have close to 90% performance of the SSDs but cost only a quarter of an SSD.

Peter