Here are the best. BTX — short for Balanced Technology eXtended — was a form factor that was coined to replace the ATX motherboard form factor in late 2004 and early 2005. Intel came up with ...
BTX: 12.8" x 10.5" -- Released in 2004 by Intel as a replacement for the ATX form factor, BTX boards brought improvements including better thermals for power-hungry parts such as the Pentium 4.