I have a 4U SuperMicro SC847 Chassi that comes with redundant 1400W power supplies. All of the internal power cables (ATX, ATX12V, HDD and such) are connected to two circuitboards where the back of the power supplies plugs into.

There is also a four cables going to a female five pin connector labeled "P4" that is not described in the manual.

I assume this is to somehow be able to monitor the PSU fans or something. Does anyone know what it's supposed to be for?

The the four cables going to the the connectors are:

  1. White/Green
  2. White/Yellow
  3. Red
  4. Black
  5. N/C

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1 Answer 1


That's a PMBus connection. Motherboards that support Power supply Monitoring can use it to report the power supply's internal information. I've only seen such connectors on SuperMicro motherboards.

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