Six months ago Intel announced the release of a new format of motherboards, the BTX (Balanced Technology Extended). This new format should substitute the current ATX standard in the next few years.

The big question is: Why a new format for motherboards?

The new format was launched for two basic reasons: first, to improve the thermal dissipation of the computer (that is, its internal ventilation). With processors that have higher and higher clock speeds, and with other components, such as video cards, memories, and hard disks, generating more and more heat in the computer, it is natural to think about a better way to refrigerate the PC. The second reason is to try to standardize the formats of small-sized motherboards, used mainly in small-sized PCs, such as Shuttle's XPC. Nowadays, motherboard manufacturers who produce small-sized PCs have two options: either they use the ITX format created by VIA or they use a proprietary format.

The BTX format has three basic sizes: picoBTX (7.9 in. x 10.4 in. – 20.32 cm x 26.67 cm), microBTX (10.3 in. x 10.4 in. – 26.41 cm x 26.67 cm) and BTX (12.7 in. x 10.4 in. – 32.51 cm x 26.67 cm). The VIA's ITX standard, which measures 8.4 in. x 7.4 in (21.5 cm x 19.1 cm), is smaller than Intel's picoBTX. The two other sizes have almost the same dimensions of the microATX and ATX, respectively.

click to enlarge
Figure 1: BTX motherboard layout.

The main difference among ATX and BTX motherboards is the position of the slots. BTX motherboards are like mirrored ATX boards. Where the connectors of the serial ports, parallel ports, keyboard, mouse, USB, etc. are soldered today we find the expansion slots in the BTX boards. And where the expansion slots are today, in BTX motherboards we find the board connectors (serial ports, parallel ports, keyboard, mouse, USB, etc.)

Another change was the distance between the motherboard and the metallic chassis of the PC case, which is now 0.4173 in. (10.6 mm), bigger than the distance in the ATX standard, which improves the flow of air in lower part of motherboard and facilitates the use of systems to fit in the cooler of larger processors.

In the ATX case, if we have the front of the case facing you, we have that the motherboard installed on the right side and the left part is "empty", that is, it is the space used for the cables and the installation of boards. In the BTX case there will be the exact opposite. The closed side (where the motherboard is installed) is the left one, and the empty one (for cables, installation of boards, etc) is the right one.

Due to these difference, BTX motherboards cannot be installed in ATX cases, neither can ATX motherboards be installed in BTX cases.

Besides, as BTX motherboards will use PCI Express slots, they will need a new power source, because motherboards with this new type of slot need a new power source, which uses a 24-pin plug (the ATX power sources use 20-pin plugs). In other words, the current ATX sources won't fit in BTX motherboards.

The migration from the ATX standard to the BTX one, however, should take long. In spite of the fact that the BTX specification is practically ready, we foresee that BTX motherboards and cases will only begin to be popular in 2006, if we take into account the same time that it took the ATX standard to become popular (the ATX standard was launched in 1995, but we only began seeing it more frequently from 1997 on).

More details of the new BTX format can be obtained at http://www.formfactors.org.