Samsung 950 pro 256gb m2 pcie nvme working @ x2 instead x4 pcie link width. Dell E7270

Yesterday I installed a Samsung 950 pro 256gb m2 pcie nvme ssd into a Dell E7270

Older configuration was with a sandisk regular sata 3 ssd. After replacement did a bios reset twice, once factory reset, once custom. (I left sata on ahci.)

I chose to install windows 10 pro x64 by using the uefi/gpt methode. Legacy options off.

Installation went without a problem. Afterwards I installed the Samsung nvme driver 1.4.7.17.

Also the Samsung magician software. It reports a link speed 8Gbps (is ok), link width 16 Gbps (should be 32?) .

Is there a way to change the pcie link width from 2x to 4x? I thought this ultrabook did support x4.

E7270 i5 6300U, 16gb ddr4, Samsung 950 pro 256

comment would be appreciated :-)  Thanks in advance!