The ATX layout rotated the CPU and memory 90 degrees, allowing full-length expansions to be plugged into all sockets. The power supply blows air over the CPU rather than pulling air through the ...

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.