msi slotThe number of the RAM slots on your motherboard. The maximum RAM size supported by your motherboard. Whether the type of memory is compatible with yourB key slot for ‘B’Key card (also known as Socket 2) (SATA) M key slot in ‘M’Key card (also known as Socket 3) (PCIe x 4) B+M Key cassettes are available for both cassette slots. Check HDD and SSD support specifications.