AMD is pushing a new motherboard format called DTX, which it says will allow system assemblers to build smaller PCs that are quieter and less wasteful of energy.

The DTX spec is intended to bolster the fast-growing market for small form factor (SFF) PCs, said Jochen Polster, AMD's sales & marketing vice president. He added that around 20 companies have already signed up to make DTX boards and cases, including Asus, Asetek, MSI, Gigabit, Elitegroup and Shuttle.

Polster said that PCs based on ATX motherboards are too big, noisy and energy-hungry. "The best argument for ATX towers is that the components are standard, and therefore cheaper than proprietary SFF boxes," he added, in a dig at the mini-ITX format championed by VIA.

With their built-in video, sound and other ports, VIA's mini-ITX boards have been popular with builders of embedded PCs – and with case-modders, who build PCs into all sorts of outlandish casings – but less so in the wider PC market.

Polster claimed that's because compact designs such as mini-ITX, which is 170mm square, are simply too small for the average technician to work with. By comparison, at 200x244mm, DTX is still big enough to see where the cables go – and to allow for expansion.

"DTX is designed to be easy to assemble and upgrade," he said. "That's very important for small system builders, who cannot deal with very small boxes."

The DTX specification is deliberately limited. It calls for the board to be manufacturable as a four-layer PCB, which Polster claimed would make it cheaper than the likes of mini-ITX, and it defines two expansion slots and an internal power supply for the PC, but nothing else apart from mounting points.

"We do define two PCI or PCI-Express expansion slots," he said. "Almost no-one uses expansion slots any more except for graphics - there are exceptions, and they will continue to use towers."

He added, "We're not interested in defining I/O or graphics on the motherboard. The builder can include PS2 ports if he wants - we think he shouldn't, but he can. We are trying to be neutral here - we want to repeat the success of ATX."