Balanced Technology Extended
New motherboard form factor created by Intel in 2003 in order to replace ATX form factor. This new form factor was released for two main reasons: first, to improve the PC thermal dissipation. The second reason is to try to standarize small form factor motherboards used by small form factor PCs (SFF), like the XPC from Shuttle. Nowadays if a motherboard manufacturer wants to produce a small form factor motherboard it has two options: to use the ITX form factor created by VIA or to use a proprietary standard.
The BTX form factor has three basic sizes: picoBTX (7.9" x 10.4" or 20.32 cm x 26.67 cm), microBTX (10.3" x 10.4" or 26.41 cm x 26.67 cm) and BTX (12.7" x 10.4" or 32.51 cm x 26.67 cm).
Figure 1: BTX form factor.