What do the large value caps around the microprocessor do?

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  • themainproblem
    New Member
    • Feb 2009
    • 4
    #1

    What do the large value caps around the microprocessor do?

    Hello gentlemen. I have been given 9 dell desktops that all look like they have leaking caps very close to the microprocessors. What do these caps do? From the printed circuit layout they look like they might be a very large filtering bank. But I don't know. They are of a large value around 1800 uf @ 6.3v. They are close in to the processor as well. The trouble symptoms are very similar will all the units. The motherboard signals an onboard fault with no boot and no video display and no HD activity. I have not seen or smelled any evidence of burning or overheating, just brown crap coming out of 5 caps.
    Thanks in advance and I apologize for the stupid question. M
    Tags: None
    • PCBONEZ
      Grumpy Old Fart
      • Aug 2005
      • 10661
      • USA
      #2
      Re: What do the large value caps around the microprocessor do?

      Hey Apache Junction!

      There are maybe 5+ different jobs electrolytic caps do on motherboards and you pretty much have it right for what you are looking at.

      Those specific ones are part of the CPU's Voltage Regulator [VRM], and yup, they are a bank of filter caps.

      There are VRM 'High Side' caps which on anything newer than P3 are 16v caps because they are on +12v power.

      The VRM 'Low Side' caps can be any voltage rating as long as it's more than the highest Vcore the board might use.

      I made a little drawing to help.
      Attached Files
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        Comment

        • aopen
          New Member
          • Mar 2009
          • 1
          #3
          Re: What do the large value caps around the microprocessor do?

          many thanx PCBONEZ

            Comment

            • themainproblem
              New Member
              • Feb 2009
              • 4
              #4
              Re: What do the large value caps around the microprocessor do?

              Thank you PCBONEZ for your reply. That helped.

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