When M2 holds a SATA-type M.2 device, SATA3_1 becomes inactive.
When M2 holds a SATA-type M.2 device, SATA3_1 becomes inactive.
Looking for all six SATA ports to connect an HDD or NAS, what does "SATA-type M.2" mean? You can still use the M.2 slot for booting, but you need to check which M.2 type supports SATA. Some M.2 slots are disabled for SATA, so verify compatibility before installing.
SATA type M.2s can block certain SATA connections because SATA is a data transfer standard, while M.2 refers only to the physical design. You can still employ NVMe M.2 devices since they operate with a separate data protocol that won’t affect the SATA ports.
M.2 is a common connector standard. M.2 SSDs may use PCIe (NVMe) or SATA interfaces. The user guide details information beginning on page 35 of the provided PDF: https://download.asrock.com/Manual/B560M Steel Legend.pdf M2_1 is compatible only with NVMe drives. M2_2 supports both NVMe and SATA, but placing a SATA SSD in that slot turns off the SATA3_1 port near the front I/O. To utilize both extended M.2 bays and dual SATA ports, use two NVMe M.2 drives.
Check the connector type on the SSD. If it has a SATA port, it’s SATA; if it uses PCIe or M.2 interface, it’s not SATA.
For SATA M.2 SSDs you frequently encounter mentions of SATA or AHCI, and the specs will indicate speeds below 600 MB/s (roughly 550 MB/s is the upper limit on SATA). As others have mentioned, the M.2 interface is built to handle either NVMe (PCI-E) or SATA-based drives, but when using the SATA version, the connections to the SATA 3.1 port are rerouted to the M.2 slot, rendering that port inaccessible.