The form factor was designed by Intel for flexibility and can be used by everything from large tower systems to those ultrasmall systems that sit under a monitor?
the answer is "BTX" and I don't care why your asking not for me to judge but you should get the right info and BTX is correct-This answer is incorrect.......The correct answer is FlexATX.FlexATX is a motherboard form factor derived from ATX. The specification was released in 1999 by Intel as an addendum to the microATX specification. It uses a subset of the motherboard mounting holes required for microATX and the same I/O plate system as ATX and microATX.FlexATX specifies that a motherboard be no larger than 9.0 x 7.5" (229 x 191 mm), and can have no more than 2 expansion slots.BTX (for Balanced Technology Extended) is a form factor for motherboards, originally slated to be the replacement for the aging ATX motherboard form factor in late 2004 and early 2005. It has been designed to alleviate some of the issues that arose from using newer technologies (which often demand more power and create more heat) on motherboards compliant with the circa-1996 ATX specification.