ATX Version 3.0 Multi Rail Desktop Platform Power Supply
PCIe* Add-in Card Auxiliary Power Connectors Sideband Signals
The new 12VHPWR connector has 4 sideband signals defined that communicate between the Power Supply and the PCIe* Card. Two of these sideband signals are required with the connector and two of them are optional from the Power Supply. The four sideband signals are:
For the most up to date and detailed description, refer to Section Section 5.3 – Optional Sideband Signal in the PCI Express* Card Electromechanical Specification, Revision 5.0. That document is available from www.pcisig.com.