Because so many people not requesting any I/O shield.
Motherboard ATX IO Shield Backplate 3 Horizontal Audio Ports USB Ports Far Right
Motherboard ATX IO Shield Backplate 6 Audio Ports Parallel LAN No SPDIF Port
Motherboard ATX IO Shield Backplate with ESATA Port LAN
Motherboard ATX IO Shield Backplate Non-Standard OEM Layout Unique Rear Ports
Motherboard ATX IO Shield Backplate 6 Audio Ports No Parallel No SPDIF Port
Motherboard ATX IO Shield Backplate Gap then 3 Vertical Audio Ports Far Right
