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I am looking at using either of these parts to connect to a server power supply. I realize a capacitor helps to regulate voltage. Why would each of these parts that have similar function not both have a capacitor. That makes me think that a capacitor is not needed.Could it possibly be due to inductance. But it still does not answer why one has and one does not.

Any input is appreciated:

With capacitor: http://www.ebay.com/itm/DPS1200FB-A-Power-Supply-Breakout-Adapter-Board-10-PCIE-Cable-fr-Ethereum-Mining-/322705408187?hash=item4b22bdc0bb:g:sS4AAOSwcQlZqoHk

Without Capacitor:

http://www.ebay.com/itm/DPS-1200FB-QB-A-12-ports-Power-Supply-Breakout-Board-Adapter-For-Ethereum-Mining-/253139686137?hash=item3af04d12f9:g:hlAAAOSw23lZsQsL

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  • \$\begingroup\$ BTW - the description for the 1st one lies. One lonely aluminum electrolytic does not make a "Solid capacitor Filter". It's not 'solid' (in any sense of the word), nor is it a filter. \$\endgroup\$ – brhans Sep 13 '17 at 21:32
  • \$\begingroup\$ thank you very much. is it next to useless? I have seen other connectors that connect only one peripheral pci device with a capacitor(not sure of size). While this can connect many more. It makes me think that the breakout board design tries to compensate for bad design in some way. unsure of course. \$\endgroup\$ – user3202058 Sep 13 '17 at 21:37
  • \$\begingroup\$ Here is the connector for one device with the capactor: amazon.com/gp/product/B01NAE4O7I/… \$\endgroup\$ – user3202058 Sep 13 '17 at 21:41
  • \$\begingroup\$ Connector with one device with many capacitors: amazon.com/gp/product/B01MU51491/… \$\endgroup\$ – user3202058 Sep 13 '17 at 21:41
  • \$\begingroup\$ It depends what peripherals and how you want to switch them On. The one with a Cap also has a switch. Are you an Ether Miner? \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Sep 14 '17 at 0:05
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You mean this one?

enter image description here

That capacitor looks pretty pointless to me. The power supply and the devices it powers should both already have filtering capacitors of their own, so one more small capacitor placed this close to the power supply won't do anything useful.

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There are dozens of server power supplies, and dozens of modifications, with extra voltages and without, with variety of standby voltages and power-on circuitry. The two boards apparently have different design and layout. What is so strange that one does have a cap, and another doesn't? It could be some power-on delay, or delay of enable of some secondary voltage. Without details and schematics it could be anything.

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I haven't noticed any capacitors on either of these boards. one shows molex type connectors only, while the other shows:

  • The same molex type conectors,
  • A dip switch (red plastic box with white levers)
  • 4x 4-pin IC's (which look like optocoupler packages)
  • Miscenaleous resistors
  • One KK type header, probably 2.54mm pitch.

If you're wondering what the white rectangular marks on the silkscreen are, My guess is that they would be jumpers. No capacitors on sight my friend.

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  • \$\begingroup\$ much obliged. you mean not molex but 6 pin connectors only right? molex are four pin. Would you recommend one over the other? \$\endgroup\$ – user3202058 Sep 13 '17 at 21:44
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    \$\begingroup\$ The 1st link clearly shows a capacitor on the 2nd and 4th images. \$\endgroup\$ – Glen Yates Sep 13 '17 at 21:48
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    \$\begingroup\$ @user3202058, there are several families of this kind of connectors made by Molex, ranging from two pins to 24 and more, Mini-Fit, Micro-Fit, Nano-Fit, with different pitch, 2.5mm 4.2mm etc. \$\endgroup\$ – Ale..chenski Sep 14 '17 at 2:19

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