BTX Form Factor: More Efficient Layout For Components
Intel already specified the BTX standard last year. While we can only expect to see BTX motherboards sporadically in the first half of 2004, if at all, BTX boards are not expected to dominate over the conventional ATX boards before 2005.
There are three reasons for making the change from the ATX form factor to BTX: general cooling deficiencies, the noise generated by cooling and the more sensible layout of components to enable smaller systems.
Some of the changes that will not be as obvious are to be found in the electrical connections. The 24 pin connector is the same as the ATX12V connector that is typically used for workstations, except that it is based on the CFX12V specification. It is different from ATX in that there are four additional connections for 3.3, 5 and 12 Volt, including the ground wire.
Although BTX compliant motherboards are based on the CFX12V standard, they still function perfectly well with normal ATX power supplies - as long as the additional 4 pin power cable is used (which will no longer be included with BTX).
Cooling has become a topic of discussion for the ATX form factor because the ATX specification does not guarantee good air-cooling in PC cases. On the contrary, it does not have prescribed paths for airflow, the power supplies differ from one another considerably in the airflow they provide, manufacturers are allowed to install various components to their heart's desire and there are also no guidelines for installing additional fans in the case. So, for example, if a PC case is designed with an emphasis on keeping costs down above all, then it probably does not offer adequate cooling for the latest processors.
At first glance, the BTX form factor may not seem to be fundamentally different from ATX. However, looking closer, the important changes can be found in the details. With BTX, the layout of the components is based on the in-line principle. This ensures that air can flow through the PC case (ideally from front to back) with the least possible hindrance. This linear layout also reduces air turbulence, which in turn lowers the noise level.
There are new specs for the power supply, based on the 24 pin connector, which is known from the ATX12V specification.