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I am going to replace the capacitor on this mainboard (see here) soon. I know that the original capacitor is a NICHICON (270UF/16V 8*11.5-12K-B). However, it is not that easy to find exactly that capacitor.

Can it be a problem to use a generic instead of an identical replacement for a capacitor on a PC mainboard?

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  • \$\begingroup\$ Link the data sheet please. \$\endgroup\$
    – Andy aka
    Jun 13 at 17:32
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    \$\begingroup\$ By definition you could use a suitable replacement, but not all generic capacitors are going to be suitable. Can you find a datasheet for that specific capacitor? Or at least something about it beyond the voltage rating? \$\endgroup\$
    – user1850479
    Jun 13 at 18:16
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    \$\begingroup\$ OP identified the capacitor as a Nichicon FP-016RE271M-KBCG in a previous question. There exists no public datasheet of that series as far as I can tell. Since these "super special" caps are part of ASRocks marketing for the mainboard, I suspect there is some exclusivity contract between Nichicon and ASRock. Or maybe this is just a different series that is rebranded for marketing. \$\endgroup\$
    – nanash1
    Jun 13 at 18:22
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    \$\begingroup\$ This is an aluminum polymer solid electrolytic. Generic 270/16v does not differentiate between the type of electrolyte.This data sheet may help identify an alternative. \$\endgroup\$
    – RussellH
    Jun 13 at 18:57
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    \$\begingroup\$ @Troutdog I highly disagree. It's not a generic bulk cap. It is a low-ESR polymer electrolytic. Likely needs high ripple current rating. Critical. \$\endgroup\$
    – Justme
    Jun 13 at 20:24

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As long as the parameters of a new capacitor are correct then you can probably substitute it in place of the original one.

The main things to consider when selecting a new capacitor are.

  • Rated voltage
  • Capacitance
  • ESR
  • Allowed ripple current
  • Rated temperature

Ideally find a capacitor where all the above factors are as close as possible to the original. If you can't find a capacitor with identical parameters follow the guidelines below.

Rated voltage: Try and make this identical to the original, but higher rating is usually OK. If using a lower voltage rating the part may fail.

Capacitance: Try and match to the original value. But ±20% would probably be OK for most stuff considering aluminum caps tend to have ±20% tolerance anyways. For bulk power supply decoupling, using a higher value (within reason) is also probably OK.

ESR: Try and get somewhere close to the original. A little more or less is probably OK. Going for a lower value could improve power supply efficiency and noise, but it could also destabilize the supply if the ESR was being used for damping/stability.

Allowed ripple current: Any value greter than or equal to the original is OK.

Rated temperature: The maximum rated temperature should be at least as high as the original part. For the lowest rated temperature you need to match the operating conditions of the device. If you don't plan to operate the device in freezing temperatures, then you probably don't need a minimum rating below 0C.

Note that capacitor lifetime decreases exponentially with operating temperature. If you can find a capacitor with a higher maximum rating than the original, it can dramatically increase the operating life of the part.

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  • \$\begingroup\$ How to choose between aluminum polymer (solid) and regular electrolytic? \$\endgroup\$
    – RussellH
    Jun 13 at 19:53
  • \$\begingroup\$ ESR and ripple are unknown unfortunately due to missing specsheets. Is ESR and ripple of a same high endurance solid capacitor similar or can there be big differences? \$\endgroup\$
    – Tintenfisch
    Jun 14 at 10:32
  • \$\begingroup\$ @RussellH Looking at the top of this capacitor its probably an aluminum polymer type. Regular aluminum electrolytic capacitors usually have a scoring on the top to vent the capacitor in case of a buildup of gasses. Search for the word "vent" in this article... eepower.com/capacitor-guide/types/polymer-capacitor/# \$\endgroup\$
    – user4574
    Jun 14 at 15:50
  • \$\begingroup\$ @user4574 I received an answer from Nichicon by the way. The capacitor is not found, it seems it is a custom 12.000 hours version from Fujitsu times. But it could be a type of RNU1C271MDNASQ they said. \$\endgroup\$
    – Tintenfisch
    Jun 14 at 16:04

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