ASRock Z97 Extreme6 Tests Samsung XP941 M.2 x4, Plextor M6e M.2 x2 and Samsung 840 Pro SATA 3 SSDs | The SSD Review
I harvested a PCIe Gen3 x2 NVMe 1.3 SSD from my older laptop, the problem is that its length is short. I've held it in place with some tape, it should hold.