ASRock 990fx Extreme9 and NVMe support

[mixsetup]

Hi there I have updated the BIOS to the P1.80 which has NVMe support.
Does this mean if I buy an adapter card so it will fit in to a PCIE slot and an M.2 drive it can boot from it?
Also if I do as the board is only PCIE 2.0 will it slow down the M.2 drive?

Thanks