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ATX Specification - Version 2.1
Page 5
Contents
1. Executive Summary ......................................................................................................7
2. ATX Form-factor Overview ...........................................................................................8
3. Layout ............................................................................................................................9
3.1 Board Size.......................................................................................................................................... 9
3.2 Mounting Hole Placement .................................................................................................................. 9
3.3 Connector Placement ........................................................................................................................ 11
3.3.1 Expansion slots ..................................................................................................................... 11
3.3.2 Power Input ........................................................................................................................... 13
3.3.3 Disk I/O ................................................................................................................................. 13
3.3.4 Front Panel I/O...................................................................................................................... 13
3.3.5 Back Panel I/O ...................................................................................................................... 13
3.3.6 Memory Sockets ................................................................................................................... 16
3.3.7 Processor.............................................................................................................................. 16
3.4 Height Constraints.............................................................................................................................. 16
3.4.1 Primary (Component) Side Height Constraints..................................................................... 16
3.4.2 Secondary (Bottom/Solder) Side Height Constraints ............................................................ 18
4. Power Delivery ..............................................................................................................19
4.1 Power Supply Connectors.................................................................................................................. 19
4.1.1 Aux Power Connector for 250 W and 300 W Configurations ............................................... 20
4.1.2 2x2 Connector....................................................................................................................... 20
4.1.3 Power Signal Control Definitions........................................................................................... 20
4.1.4 Voltage Tolerances ............................................................................................................... 21
4.2 Optional Power Connector ................................................................................................................. 21
4.2.1 FanM Signal .......................................................................................................................... 22
4.2.2 FanC Signal .......................................................................................................................... 22
4.2.3 3.3 V Sense Line................................................................................................................... 23
4.2.4 1394 V Pin............................................................................................................................. 23
4.2.5 1394R Pin ............................................................................................................................. 23
5. Other ATX Chassis Considerations.............................................................................24
5.1 Venting ............................................................................................................................................... 24
5.2 Power Supply Mounting ..................................................................................................................... 24
6. Additional Information..................................................................................................24