As I’m on a constant fight with dust in this dirty city, my PC needs a good cleaning every couple of months. Today I decided that it was time to give it a thorough cleaning, since the fans were roaring inside — a clear indication that dust has built up on them. As usual, I was performing a quick visual inspection on the motherboard before putting everything together again, when something caught my attention: one of the large capacitors near the processor looked a little different. Its aluminum cap, normally flat, was bulging out and was covered in some orange foam.
Ut oh, this is bad. In time, electrolytic capacitors slowly turn defective because of the heat, and one sign of this malfunction is the swelling on top, losing electrolyte which corrodes the aluminum (the foamish-like stuff) or even exploding. On a computer motherboard, these capacitors are critical components for the voltage regulators that provide the processors with over 100 watts of power, heating up even to 120 degrees Celsius in the process. If the capacitors fail, then the voltage regulators will not supply the processor with the correct voltages, and the processor, motherboard, memory and even video card will malfunction.
On a side note: the difference between a reputable brand and a no-name manufacturer of motherboard usually consists of the quality of small components such as these capacitors, while the design and important components is almost identical. The no-name manufacturer will use cheaper components that will most certainly fail a lot faster than the quality components used by reputable manufacturers. So, if you decide on a PC Chips or Matsonic or Albatron or MicroStar (MSI) motherboard, saving a few dollars on these cheap brands exposes you to a high risk of the entire system going KABOOOOM. Such situations occur less often with motherboards like Tyan, Gigabyte, Chaintech, Epox, Asus and others. My motherboard is an Epox, but it’s already a few years old — I’m happy it has survived so long without any problems.
Anyway, back to the story. I took out the motherboard and checked all large capacitors closely. Apart from the one losing electrolyte, 3 others were swollen on top. I decided to unsolder all 14 capacitors; among the ones I thought were still good, one was swollen at the bottom! Tomorrow I’m going to an electronic store to buy replacements.
Whew!! I don’t know how long the system would have continued working like this, but it certainly was a matter of months, maybe weeks before the processor burned up from the abnormal voltage and overheating. I feel lucky to have discovered this problem. The new capacitors will cost a total of 2, maybe 3 dollars, but they are critical for making a few hundred dollars worth of technology function properly.
[Later edit] I bought new capacitors for almost $4, soldered them on the motherboard nicely, and I’ll be monitoring voltages and temperatures to see if the board runs at normal parameters. I’m so happy!
Be warned, though; what I have done — messing with the components on the motherboard — is definitely not recommended for the average user! Have your motherboard replaced if it’s still under warranty, but do not try to unsolder and solder components if you are not experienced at this and if you don’t have the proper tools for it (like a temperature-controlled Weller soldering station)! Motherboards and generally computer boards are extremely fine components, with 4 or even 6 layers of circuits and covered with miniatural Surface Mount Devices (SMDs). Applying too much heat or being clumsy at handling the hot iron can destroy the fine circuits or knock off some other components, and there is no fix to those mistakes! Dad’s an electronic engineer and I’ve been playing with circuit boards since I was 4, yet I still kept my fingers crossed when I pushed the Power button after this operation. Don’t try it at home unless you have the experience needed to keep risks to a minimum.
[Two weeks later edit] I finally managed to get hold of the digital camera and take a few photos of the capacitors. Unfortunately, it can’t take macro photos closer than one inch or so, and the detail is not as good as I’d like, but I still hope you can make out the differences.
In the photo below, the two capacitors on the left have their tops swollen; the one on the right is how they should normally look like: flat.
Here are the bottoms of the capacitors. Again, the two on the left clearly have the black rubber caps swollen, while the one on the right appears flat. As they were mounted tightly onto the circuit board, the swelling underneath did not become visible until I removed them from the board. In the photo, all three rest on the flat desk, you can see how the capacitor at the right stands up right while the other two are tilted because they stand on the bulging tops seen in the previous photo.
The original capacitors were green with yellow markings. I have no idea about capacitor manufacturers, and I was only able to find one kind to buy, so that had to work. I bought replacements with exactly the same specifications: capacity, voltage and maximum temperature. My concern was with their size — their diameter, to be exact; new ones had to be of the exact girth or slimmer than the originals, otherwise they wouldn’t fit tightly next to each other on the motherboard. In the photo below, you can see the new capacitor on top, black with white markings, and the original one on the bottom, green with golden markings; they are the same diameter, although the new model is shorter. No problem there.
[Much later edit] The problem I have described above is more frequent than you would imagine. BadCaps.net goes into more detail about the problem and also offers repair services. I guess I have just saved $45 + shipping 
