Capacitor Plague is an informal term used to reference the common premature failure of certain brands of Electrolytic capacitors used on some PC motherboards and video cards. An incorrect electrolyte formula causes the production of hydrogen gas, leading to buldging or disformation of the capacitor's case, and eventual venting of the electrolyte.

Identifying "Capacitor Plague"

The most common way of identifying capacitors failing due to this cause is physical deformations:

• Buldging of the vent on the top of the capacitor
• Sitting crooked on the motherboard as the bottom rubber plug is pushed out
• Electrolyte (visible as brown gunk) leaked onto the motherboard from the base of the capacitor
• Venting from the top of the capacitor, visible as brown deposits, or a visible hole in the vent

As the capacitor ages, its capacitance decreases while its effective series resistance (ESR) increases. When this happens, the capacitors no longer adaquately serve their purpose of filtering the voltages on the motherboard, and system instability results. Some common symptoms are:

• Not turning on all the time; having to hit reset or try turing the computer on again
• Instability (hangs, BSODs, kernel panics, etc), especially ones which get progressively worse with time
• Vcore or other system voltages fluctuating or going out of range, possible with an increase in CPU temperature as the core voltage rises
• Memory errors, especially ones that get more frequent with time
• Spontaneously rebooting
• Failing to complete the POST, or rebooting before it is completed
• Never starting the POST; fans spin but the system appears dead

Unlike the physical signs, which are conclusive evidence the capacitors are failing, many of the operational signs may be caused by other factors, such as a failing power supply, dust clogging a fan, bad RAM, or other hardware problems. Instability once the operating system has loaded, especially on Microsoft platforms, may indicate a software problem and not a hardware problem at all. If any of these symptoms are experienced, removing the system's case, and inspecting the capacitors, especially those around the CPU, may immediately identify capacitors as the cause. If there are no physical signs, an oscilloscope may be used to examine the voltage on the capacitors, with excessive ripple voltage being a sign the capacitors are not doing their job.

Cause of the failing capacitors

The primary cause of these problems is industrial espionage gone wrong, with some taiwanese electrolyte manufactures using a stolen formula that was incomplete, and lacked ingredients needed to produce a stable capacitor. IEEE's Spectrum has an overview of the situation, aptly titled Leaking Capacitors Muck up Motherboards, after the tendency of the capacitors to leak gunk (electrolyte) onto the motherboard.

However, once the problems with these capacitors became known, there is evidence that motherboard manufacturers continued to use the bad capacitors, despite knowing they would certainly fail in a short time span. Only ABIT has admitted to the problems, while other manufacturers have given responses ranging from pretending nothing happened to strongly denying it and issuing legal threats to web sites mentioning their names in conjuction with capacitor failures.

When the capacitor is charged, the water-based electrolyte becomes unstable, and breaks down producing hydrogen gas. Since an electrolytic capacitor of the kind found on motherboards is sealed, the pressure builds up within the capacitor. As the pressure grows, the flat metal tops of the capacitors begin to bend, or the rubber sealing plug is pushed down. Eventually the pressure exceeds the strength of the case, and venting occours, either by blowing out the rubber bottom of the capacitor, or bursting the scored metal vent on the top of the capacitor. Depending on exactly when this happens, effects can range from a pop and a hissing noise to a small explosion. Venting is typically messy, and the electrolyte must be cleaned off the motherboard to prevent further damage.

Replacement of failing capacitors

A few repair shops specialize in replacement of motherboard capacitors, however most will simply diagnose the system as needing a new motherboard. Also, in many cases, the cost of having a technician repair the board exceeds the cost of a new replacement board. Due to these factors, many people choose to replace the capacitors themselves.

While this article is not (at present) a tutorial, guides and hints to do this can be found in the external links section. However, a disclaimer is appropriate: Soldering on motherboards, which are typically six or more layers, can be challanging, and without the right equipment or adaquate skill, can easily render a repairable board into an unrepairable one. Before replacing the capacitors on a motherboard (typically referred to as "recapping"), you should take the time to research the proper replacements and soldering methods.

Commonly failed capacitor brands

• Tayeh (A brand that does not appear to exist, indicating the actual manufacturers were leary of putting their name on their product)
• Chhsi
• Teapo (Teapo has denied these claims, and evidence suggests their new capacitors are sound, however their older ones appear to suffer from the same problems other brands do)
• I.Q.
• Rulycon (A clone of "Rubycon", a well-known manufacturer of high-quality capacitors, right down to the exact style of the cases and the fonts used for lettering)
• JPCON
• Jackcon (The only capacitor manufacturer to own up to their mistake; they are also the only one to issue free replacement capacitors to people who had theirs fail. Their new products appear to be of greater quality.)
• JDEC
• CTC
• (G) Luxon
• Gloria
• Raycon
• Hermei
• Choyo
• GSC
• Nrsy

A few of these are from the list at BadCaps forums, to fill in the ones the author has not personally seen.

If you have a motherboard with any of these capacitor brands, there is a good chance it may fail prematurely.

Typically, only the capacitors over 480uf fail, since the lower capacitance ones are usually made with a different electrolyte. When motherboards are recapped, only the ones over 480uf are replaced for this reason.

What happens after capacitors fail

While failing capacitors typically results in the aformentioned system instabilities, occasionally a capacitor fails such as to form a short circuit, frequently destroying the motherboard's onboard voltage regulators or the system's power supply. The normal failure mode of the onboard voltage regulator is for the MOSFET to also short circuit, causing the system's power supply (5 or 12 volts depending on the motherboard) to be applied directly to the CPU, northbridge, RAM, or other components, causing damage or destruction. As such, a motherboard with symptoms of failing capacitors should be taken out of service until it is repaired, to prevent further damage.

External links

• BadCaps A repair site offering tutorials on proper soldering and replacement capacitor selection