Balanced Technology Extended

The BTX: MotherBoard [Balanced Technology Extended] format is 325.12mm wide x 266.70mm deep.
The BTX mother board was developed to replace the ATX: form factor.
How ever don't expect to find many BTX main-boards, as were they never really accepted.

The new BTX format addresses many of the ATX issues, including improved scalability, thermal placement, Acoustic Performance, and increased area for heat sinks. Three motherboard form factors are allowed with BTX:
...BTX: (Balanced Technology Extended) 325.12mm wide x 266.70mm deep [Holds 7 Add-On card]
........microBTX: (Balanced Technology Extended) 264.16mm wide x 266.70mm deep [Holds 4 Add-On card]
........picoBTX: (Balanced Technology Extended) 203.20mm wide x 266.70mm deep [Holds 1 Add-On card]

Normal ATX motherboards do not work in BTX systems. The BTX case differs greatly from those designed for ATX mother boards. The BTX mother board layout is completely different from that of ATX. Air flow and air ducting is entirely different. A Support and Retention Module [SRM] is also required with BTX motherboard designs. The SRM plate resides beneath the processor to support the mother board and thermal module.

A number of different Power Supplies may be used with the BTX form factors. The power supplies will indicate the standard which they comply to, in this case the notation ATX12V indicates the power supply compiles with these pinout tables. The BTX size board will use either the ATX12V, or SFX12V power supplies. For the Small Form factor [SFF] board sizes the power supply will be the CFX12V or LFX12V form factors. The board was rotated in the Chassis to allow for improved air flow. Pin out tables for ATX connectors are listed below.

Additional Mother Board form factors and processor types are listed on the OEM MotherBoard Manufacturers page.
By mid 2005 there were still not many takers for the BTX format. In 2006 Intel announced it would be dropping support for the BTX format in 2007.
Additional companies have also expressed a desire to drop their support.

The table above provides the ATX12V pinout for a BTX Mother Board.
The alternate Main Power Pinout for the BTX Motherboard is shown at the end of the page on a 24 pin Molex connector.

The power connector for the Floppy drive on an ATX mother Board is shown below.

The BTX power connector for the Fan is shown below. The third sensor pin is relatively new and allows the mother board to adjust the speed of the fan as the case/IC temperature changes. Pin 3 may not always be available, but the table provides the ATX pinout.

The power connector for the Serial ATA drive is shown below. The Serial ATA [SATA] Hard Disk Drive [HDD] is the new standard for Hard disk drives, using a serial interface [instead of the large parallel flat ribbon cable of the past]. This is the ATX pinout for SATA power, refer to the SATA page for the signal pinout.

The table above provides the CFX12V pinout for a BTX Mother Board.
The alternate Main Power Pinout for the BTX Motherboard is shown at the top of the page on a 20 pin Molex connector.
Note that the +12V Power Connector is the same as listed above.
+5VSB is a Standby voltage supply.
PS_ON# is an active low TTL compatible signal that allows the motherboard to enable the three main power supplies.
PWR_OK is a TTL compatible signal.

Memory Module formats and manufacturers:
Memory Module Manufacturers page.

To save money and reduce operating costs some computer manufacturers may use non-standard or proprietary components in their systems. The pinout for the power headers listed above comply with the BTX specification. However some companies may use pin outs that differ from the pin out tables above. First try to determine the pin out of the headers listed above from the manual that shipped with the computer, and use these tables only after checking all the manufacturing sources of OEM data.

So in no way is the BTX specification obsolete, and it's not even that out-dated.
But the computer industry went in a direction toward the Small Form Factor Boards [SFF], or stayed with the ATX form factor.
The BTX Physical Interface just didn't catch on with vendors, so there was no market.
In any case the pinout, interface description and signal assignments remain valid as shown above.

Home
Distributors	Components	Equipment	Software	Standards	Buses	Design	Reference