It has three sata ports on motherboard for three sata drives. The 3.5 bay has two sata power connectors. If you use a 3.5 to 2.5 adapter you can install two 2.5 drives in the same bay. Additional one 2.5 bay with only one sata power connector. Total up to three 2.5 drives or two 3.5+2.5 drives.