I'm using a computer PSU to power several controller boards and sensors. To be more precise, I'm using the 24pin ATX connector wires to power everything.

There are two 12V+ wires coming from the connector. I've noticed that one of these wires is connected to a ground wire via a capacitor. While the other wire is just a stand alone 12V+. I assume the capacitor is to smoothen the power supply on that wire?

Can anyone explain the reason for the capacitor?

  • \$\begingroup\$ Who put the capacitor there? \$\endgroup\$ – Finbarr Oct 22 '19 at 9:09
  • \$\begingroup\$ Corsair, the manufacturer of the PSU. \$\endgroup\$ – user463102 Oct 22 '19 at 9:17
  • \$\begingroup\$ Capacitors between +12 V and GND in an ATX power supply are intended for supply filtering. Although you didn't find any yet, the other 12 V line will also have such smoothing capacitors. That capacitor you found is probably there since there was no other place to put it. \$\endgroup\$ – Bimpelrekkie Oct 22 '19 at 9:21
  • \$\begingroup\$ Thank you Bimpelrekkie. \$\endgroup\$ – user463102 Oct 22 '19 at 9:24
  • \$\begingroup\$ It is not clear from the description where the capacitor is. Outside the PSU? Inside? But in either case, if it is old PSU it most likely has single 12V rail, which means all yellow wires are connected together anyway, so the capacitor location does not matter much \$\endgroup\$ – Maple Oct 22 '19 at 9:24

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