Big Sur issue with Samsung 970 evo plus

Hi guys,

I have a brand new Hackintosh and a strange problem appears with my Samsung 970 evo plus 256Go.
Writing speed is droping for no reason, and reading speed seems a little bit under his capabilities (see screenshot).
Do you have any idea what could cause this problem ?
I have the feeling its arriving especially with big files, in Disk Speed Test writing speed is around 2100 MB/s with 1Gb files, but larger speed is droping.
Firmware is up to date for the SSD.

Thanks for your help !

Suma

Author: sumadark