Concept
Mini-ITX is a motherboard form factor developed by VIA Technologies in 2001. Mini-ITX motherboards have been traditionally used in small-configured computer systems. Originally, Mini-ITX was a niche standard designed for fanless cooling with a low power consumption architecture, which made them useful for home theater PC systems, where fan noise can detract from the cinema experience. The four mounting holes in a Mini-ITX board line up with four of the holes in ATX-specification motherboards, and the locations of the backplate and expansion slot are the same (though one of the holes used was optional in earlier versions of the ATX spec). Mini-ITX boards can therefore often be used in cases designed for ATX, micro-ATX and other ATX variants if desired. Mini-ITX motherboards have only one expansion slot. Earlier Mini-ITX motherboards had a standard 33 MHz 5V 32-bit PCI slot, whereas newer motherboards use a PCI Express slot. Many older case designs use riser cards and some even have two-slot riser cards, although the two-slot riser cards are not compatible with all boards. Some boards based around non-x86 processors have a 3.3V PCI slot, and the Mini-ITX 2.0 (2008) boards have a PCI-Express ×16 slot; these boards are not compatible with the standard PCI riser cards supplied with older ITX (Information Technology eXtended) cases. The HiFive Unmatched RISC-V computer uses a Mini-ITX form factor. In March 2001, the chipset manufacturer VIA Technologies released a reference design for an ITX motherboard, to promote the low power C3 processor they had bought from Centaur Technology, in combination with their chipsets. Designed by Robert Kuo, VIA's chief R&D expert, the 215×191 mm VT6009 ITX Reference Board was demonstrated in "Information PC" and set-top box configurations. At that point, few manufacturers took up the ITX design, but Shuttle, Jetway, etc. produced many ITX based cube computers. Other manufactures instead produced smaller boards based on the very similar 229×191 mm FlexATX configuration.
