Supermicro has a special expansion port on some motherboards called a Universal I/O port. With a special riser card, a motherboard “extension” can be attached to the board to provide extra functionality. The cards actually work much like normal PCI-express cards but are inverted to fit at the bottom of a chassis. The term “motherboard extension” rather than a normal PCI expansion is used to outline the fact that all of the board’s PCI slots remain available to use ater the insertion of the UI/O card.
With the correct combination of chassis and motherboard, users of these special boards and risers are awarded unique benefits. That is, the ability to have 2 x full size expansions in some 1U chassis.
For instance, a person creating a high capacity network appliance my go to a bulkier 2U or 3U chassis to add enough NICs to the system.
With this UI/O setup, a 4 port UIO card and a 4 port PCI-e card can be put into the system to add on 8 x NIC slots to whatever is already offered on the board.
Another example would be that RAID UI/O cards are also offered by Supermicro for some of their UI/O boards. Using one of Supermicro’s proprietary UI/O RAID controllers saves the user the pain of spending more money on a 2U to 4U server to get an extra PCI slot out of their motherboard. With a UI/O RAID the extra PCI slot can be used to put an additional expansion thereby greatly expanding the utility of a 1U server.
