Samsung evo 970 too slow on alpha

Greetings everyone! So i`ve got a LP alpha 8100y with MacOS installed on it and I`m booting it from a samsung EVO 970 500Gb. Everything is working fine but there`s just one thing that bothers me: this ssd was supposed to have 3500 mb/s read and 2500 mb/s write speeds, but I`m only getting about 1500 mb/s read and 1400 mb/s write on it. Is anyone else having the same problem??
I`ve read that this is common when you use an ssd in a pcie x2 configuration but as far as i know, panda has a pcie x4 ssd slot, right??

Thank you for the attention!