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What is a Capacitor?



    A capacitor is a small electrical component on your motherboard that can perform various functions. First of all, capacitors condition DC voltage to the components and thus provide a steady power supply. Electrical components are very sensitive to voltage swings, and as such a power spike can kill those expensive parts. We don’t want that now, do we? Therefore a capacitor is placed inline to the component, allowing for absorbing of spikes and supplementing valleys, keeping a constant power supply to the component.


Second, a capacitor can store an electronic charge to be discharged at a later date. Think of a camera flash for example. A typical battery cannot release large amounts of electrons at any given point in time, and therefore a capacitor is installed into the camera to build up a charge, which is then released all at once for the flash. Remember when you couldn’t take a picture for a few seconds when using a flash? The capacitor needs time to build it’s charge from the battery, and therefore it is not ready to discharge yet.


The most common use of capacitors on motherboards is for conditioning power to the components, and if the capacitor is bad, it will not condition the power. If you put a suck on the power, such as engaging in graphics intensive applications, the capacitor is drained of its reduced capacity and the component loses power, thus shutting down the PC or freezing the screen.


What to look for


Now that you understand some of the problems that the faulty capacitors may cause, you may be wondering if there is anything you can do to verify that your board has a problem. There is!


If you are not afraid to open your computer box, go ahead and open it up. You will take the left side panel off if the computer is facing you. Once you have the panel off, you will notice directly across from you, connected to the other panel, a large circuit board with several attachments. This is your motherboard. Look on the motherboard for the capacitors, which look like miniature batteries, or pop cans. They may be of varying heights and diameters, but in general are 1 inch in height and 1/4” to ½” in diameter. Do any of these capacitors have visible leakage? If this has occurred, it will look similar to what a leaky battery looks like, with rusty corrosion along the body of the capacitor. You will also notice a browning of the board and capacitor, and it may look like a liquid has run down the motherboard.cap3bustedcapscap4    Bad_Capacitor_01 









Another sure-fire way to tell is if the capacitor has bulged. In general the capacitors will fail at either the top or bottom seal. If the top seal has bulged, it is pretty self-explanatory what you would see. Imagine a pop can left in the freezer. If the bottom seal has bulged, the capacitor will no longer be sitting flush with the board and will be pushed away and cocked at an angle. Finally, the weak point may be in the side, resulting in a bulge out the side of the capacitor. Basically, if the capacitor does not resemble a pop can, it has probably failed and bulged.


If you are having issues and with your PC and you do not see any of the above, you are in luck, sort of. Your capacitors have not failed! However, this probably means that you have bigger problems, either with the OS or hardware compatibility.




What can I do if the capacitors are bad?


You have three choices, assuming that your system is out of warranty:


1. Find and solder on a replacement capacitor. This is generally not recommended, as someone who does not know what they are doing or have the proper tools will probably create more problems than they cure trying this approach.


2. Send the board in for capacitor replacement. If you have a pre-built system, this may be the way to go, particularly if your system is still under warranty. Tell the customer service rep right away you have bulged capacitors and you will forego a lot of troubleshooting by you and the tech. They know this is a problem and will send a replacement and a tech to changeout the board. If you bought the board and do not want to RMA it, you can also send this into several specialty service folks to have them replace the capacitors. 


3. Replace the motherboard. If this was your own purchase and you have the original box, ask the manufacturer for an Return Merchandise Authorization form. Send in the old board, and they will more than likely send out a replacement, and all you have to pay is shipping. Most do not do cross-shipment, so you will be without a PC for a while! Maybe you should take this opportunity to upgrade to a newer chipset, anyway!