Mini-ITX boards can often be passively cooled due to their low power consumption architecture, which makes 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.
The form factor has provision for one expansion slot, conventionally a standard 33 MHz 5V 32-bit PCI slot. Many 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 cases.
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 form factors. He would later go on to design the Mini-ITX form factor. The ITX form factor was never taken up by manufacturers, who instead produced smaller boards based on the very similar 229×191 mm FlexATX form factor.
In October 2001, VIA announced their decision to create a new motherboard division, to provide standardized infrastructure for lower-cost PC form factors and focus on embedded devices. The result was the November 2001 release of the VT6010 Mini-ITX reference design, once again touted as an "Information PC", or low cost entry level x86computing platform. Manufacturers were still reticent, but customer response was much more receptive, so VIA decided to manufacture and sell the boards themselves. In April 2002 the first Mini-ITX motherboards—VIA's EPIA 5000 (fanless 533 MHz Eden processor) and EPIA 800 (800 MHz C3)—were sold to industrial customers.
Enthusiasts soon noticed the advantages of small size, low noise and power consumption, and started to push the boundaries ofcase modding into something else—building computers into nearly every object imaginable, and sometimes even creating new cases altogether. Hollowed out vintage computers, humidors, toys, electronics, musical instruments, and even a 1960s-era toasterhave become homes to relatively quiet, or even silent Mini-ITX systems, capable of many of the tasks of a modern desktop PC.
Mini-ITX boards primarily appeal to the industrial and embedded PC markets, with the majority sold as bulk components or integrated into a finished system for single-purpose computing applications. They are produced with a much longer sales life-cycle than consumer boards (some of the originalEPIAs are still available), a quality that industrial users typically require. Manufacturers can prototype using standard cases and power supplies, then build their own enclosures if volumes get high enough. Typical applications include playing music in supermarkets, powering self-service kiosks, and driving content on digital displays.
VIA has continued to expand its Mini-ITX motherboard line. Some of the earlier generations included the original PL133 chipset boards (dubbed the "Classic" boards), CLE266 chipset boards (adding MPEG-2 acceleration), and CN400 boards (which added MPEG-4 acceleration). Second generation boards featured the EPIA M, MII, CL, PD, TC and MS — all tailored to slightly different markets. Legacy VIA boards use their x86-compatible CPUs — the C3, C7 or low-power Eden variants, with newer boards featuring the VIA Nano CPU, launched in May 2008. Other manufacturers have also produced boards designed around the same form factor, using VIA, but also Intel, AMD, Transmeta and PowerPCtechnology.
Intel has introduced a line of Mini-ITX boards for the Atom CPU, which demonstrates a significant increase in processing performance (but without added power consumption) over older VIA C3 and C7 offerings and is key to making the form factor viable for use in personal computers. Other manufacturers saw the potential of the form factor and followed suit, some even not limiting themselves to the Atom, as evidenced by Zotac GeForce 9300-ITX board that supports Core 2 Duo CPUs with FSB frequencies up to 1333 MHz, two separate-channeled 800 MHz memory slots and fully functional PCI Express 2.0 x16 slot that could connect through SLI to the onboard video. This new wave of offerings has caused Mini-ITX to explode in popularity among home users, hobbyists and even overclockers.
Intel is currently one of very few manufacturers of Mini-ITX mainboards that also include the mechanical dimensions in their manuals.
The Mini-ITX standard does not define a standard for the power supply, though it makes some suggestions of possible options. Conventionally Mini-ITX boards use a 20- or 24-pin "original ATX" power connector. This is usually connected to a DC-DC converter board which in turn is connected to an external power adapter. Generally both the power adapter and the DC-DC board are supplied with the case.
Some boards have built in DC-DC converters and converters have also been made to plug directly into the ATX connector (e.g. the PicoPSU), either of these options avoids the need to mount a separate DC-DC converter into the case, saving space and design effort. Boards using full-power Intel or AMD CPUs typically use ATX12V 2.x connections and require a case with appropriate power supply and cooling for these more power-hungry chips.