Server Power Supply Pinout

While dumpster diving the electronic scrap I find always interesting parts.

Last week I found some rack server with hot swap power supply. I removed the power supplies and reverse engineered the pinout of them.

On the following pictures you see the power supply and their pinout.

At the moment there are only the power and power-on pins known. The other unknown pins could be SPI or I2C for handling status information of the power supply or to regulate the cooling fan speed.

The power-on pins are often the shorter pins. They have to be shorter, because if the power supply is hot plugged, they should connect last after all other pins are already connected.

Power Supply Emerson 7001540-J000
+12V 40A
+5.1V 30A
3.36V STBY 0.45A


Power Supply HP DPS-460EB A
+12V 38.3A
12V STBY 2.5A


Power Supply HP DPS-750RB A
+12V 62.5A
+12V STBY 2.5A


Power Supply Supermicro PWS-1K21P-1R
+12V 100A


5 thoughts on “Server Power Supply Pinout”

  1. Hello, for HP_DPS-460_HP_DSPS-750 i can see a resistor in your photos. How is connected?

    I connect pin 1 and 4 but power supply does not start. The power supply is OK.

    Thank you.

    1. Hi Manuel

      The switch connects with a 100 ohm series resistor pin 1 and 4 of the power supply.
      I tested again if the power supply switches on without the resistor (with a direct connection of pin 1 and 4) and it worked.
      But it could be more stable, if you use a resistor. The resistor shouldn’t have more than 100 ohms else it won’t work.


  2. Hi Simon, thank you for you reply.

    YES ! 🙂 i have started it two times without the resistor. Later i will use a resistor to try it again and see if starts allways.

    But i have to connect pins 1 and 4 for various seconds until PS starts. Is it normal?


  3. Ok. Now all is working fine. Yes, power led start inmediately, and 12V DC.

    Thank you for your help.

Leave a Reply

Your email address will not be published. Required fields are marked *