ASATA (0,1) PORTS = Connected to the CPU
SATA (0,1,2,3) PORTS = Connected to the B350 Chipset
Both set of ports are SATA-3
If using an M2 drive (non PCIEx2 or PCIEx4 signalling), then SATA (3) can't be used.
If using an M2/NVME drive (that uses PCIEx4 signalling), then ASATA (0,1) can't be...