The motherboard is quite old so doesn’t have NVMe support. The M/B doesn’t have any SATA3 headers, they are all SATA2 (this is the reason for the PCIe SATA3 adapter). The SATA adapter has native support in Linux, no additional drivers are necessary. I know this from here:
http://www.highpoint-tech.com/USA_new/series_r600-download.htm
I will plug the SSD into the mptherboard SATA2 ports.
Is there an SATA3 expansion card that you can rtecommend for use with SanDisk SSDs for optimum performance?