Solid caps vs electrostatic caps (computer psu)

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  • budm
    Badcaps Legend
    • Feb 2010
    • 40746
    • USA

    #21
    Re: Solid caps vs electrostatic caps (computer psu)

    But aren't those 5V, 3.3 are minor rails low current not the 3.3V heavy current output?
    http://home.coolpc.com.tw/fb/FSP/HEX...XA-HA550-3.jpg
    So if I look at it correctly, the combined 3.3V and 5 output power is 100W so then what you will have left is 450W for the 12V?
    I can see pro and con in that design.
    Last edited by budm; 12-20-2017, 02:52 PM.
    Never stop learning
    Basic LCD TV and Monitor troubleshooting guides.
    http://www.badcaps.net/forum/showthr...956#post305956

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    http://www.badcaps.net/forum/showthr...999#post300999

    Inverter testing using old CFL:
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    Comment

    • Per Hansson
      Super Moderator
      • Jul 2005
      • 5895
      • Sweden

      #22
      Re: Solid caps vs electrostatic caps (computer psu)

      It's basically a requirement for handling the low power states of Haswell CPU's and later. (C6 & C7).
      Group regulated PSU's can't handle such a load.

      Pretty much all modern ATX power supplies use DC-DC conversion for the 3.3v and 5v.
      Of course you need to "upsize" the 12v to compensate for it.
      "The one who says it cannot be done should never interrupt the one who is doing it."

      Comment

      • budm
        Badcaps Legend
        • Feb 2010
        • 40746
        • USA

        #23
        Re: Solid caps vs electrostatic caps (computer psu)

        Con: the power dissipation of the rectifier for that 12V will be pretty high.
        Do they implement the Synchronous Rectification some how to help reduce the power loss?
        Attached Files
        Last edited by budm; 12-20-2017, 04:13 PM.
        Never stop learning
        Basic LCD TV and Monitor troubleshooting guides.
        http://www.badcaps.net/forum/showthr...956#post305956

        Voltage Regulator (LDO) testing:
        http://www.badcaps.net/forum/showthr...999#post300999

        Inverter testing using old CFL:
        http://www.badcaps.net/forum/showthr...er+testing+cfl

        Tear down pictures : Hit the ">" Show Albums and stories" on the left side
        http://s807.photobucket.com/user/budm/library/

        TV Factory reset codes listing:
        http://www.badcaps.net/forum/showthread.php?t=24809

        Comment

        • Per Hansson
          Super Moderator
          • Jul 2005
          • 5895
          • Sweden

          #24
          Re: Solid caps vs electrostatic caps (computer psu)

          AFAIK all ATX supplies with 80+ Platinum and higher rating have DC-DC designs for the minor rails.
          And they all also employ Synchronous Rectification, I think the Seasonic X series was first on the market with it in 2009.
          I honestly don't think it's possible to design a true 80+ Platinum PSU with full range input without it.

          So that speaks in favor that the efficiency loss is extremely minor.
          Remember that you can design a DC-DC module with very close to 100% efficiency.
          But the same can't be done with a AC>DC conversion (or wise versa)

          Also remember that while there is some loss in DC-DC conversion there is also loss in the coils required for a group regulated unit.
          "The one who says it cannot be done should never interrupt the one who is doing it."

          Comment

          • Stefan Payne
            Badcaps Legend
            • Dec 2009
            • 1267
            • Germany

            #25
            Re: Solid caps vs electrostatic caps (computer psu)

            Originally posted by Per Hansson
            AFAIK all ATX supplies with 80+ Platinum and higher rating have DC-DC designs for the minor rails.
            Nope, there's one exception, Antec Earthwatts Platinum.

            Its even most 80plus Gold units have DC-DC, I only know of the FSP Aurum Plattform that isn't DC-DC...

            Comment

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