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How to Troubleshoot and Fix No Power to Your Computer’s Motherboard

written by: John Garger•edited by: M.S. Smith•updated: 5/18/2011

There are several reasons why your computer’s motherboard is not receiving power from your power supply. Read on to learn how to troubleshoot this common problem.

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    More and more home computer users are opting to build their own computer rather than buying one from the major computer retailers. The result can be a significant drop in price and the ability to customize the computer to the builder’s needs. No doubt, the home computer builder runs into routine and non-routine problems and needs to troubleshoot them without the aid of tech support.

    Like all components in a computer, the motherboard receives its power from the computer’s power supply. The power supply is the sole source of power and is, therefore, an integral part of the computer-building process. As with many aspects of building a computer, problems with the motherboard receiving power from the power supply are inevitable. Sometimes, the motherboard is not receiving power from the power supply at all and sometimes the problem is intermittent. Read on to learn how to troubleshoot no power to the motherboard.

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    Ruling Out the Obvious Causes of No Power to the Motherboard

    Before you begin troubleshooting no power to your motherboard, you need to rule out obvious causes of the problem. First, check that the power supply is plugged into a power socket and that the switch on the back of the power supply is in the “on" position. Second, be sure that the main power plug from the power supply is properly inserted into the motherboard’s main power socket. Third, be sure that all other components in the computer are connected to the correct plugs from the power supply. Finally, be sure that the 12v power connector from the power supply is connected to the CPU input connector on the motherboard. Once you eliminate these obvious causes, you can begin troubleshooting the no power problem.

    There are two main causes of no power to a motherboard. Either the problem rests with the motherboard, or it rests with the power supply. Read on to troubleshoot the most common causes to your motherboard not receiving power from the power supply.

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    Motherboard Causes to No Power to the Motherboard

    One of the most common problems of no power to a motherboard rests with the connection of the power supply to the motherboard. Most motherboards have either a 20-pin or a 24-pin female connector soldered directly onto the board. To connect the power supply’s main power connector to the motherboard, you must have a matching 20-pin or 24-pin connector on the power supply.

    Luckily, many modern power supplies come equipped with the ability to connect to either a 20-pin or 24-pin connector on the motherboard. This is accomplished by the ability to disconnect 4 of the 24 pins on the power supply’s connector. If you have a 24-pin connector on the motherboard you leave the 24 pins connected on the connector. If you have a 20-pin motherboard, you need to detach the extra 4 pins. Many times, inexperienced computer builders will connect only 20 pins into the motherboard’s 24-pin connector.

    Sometimes the motherboard receives no power from the power supply because the motherboard itself is damaged. Your motherboard contains many capacitors. The capacitors are those tiny barrel-shaped components sticking straight up on the motherboard. Look to see if any of these capacitors are broken open on top. If so, it is likely that the motherboard received a serious spike in power, thereby breaking open the capacitor. If so, that broken capacitor may be responsible for the malfunctioning motherboard. Unless you are a skilled electrician, it is unlikely that you will be able to fix the broken capacitor. Your only option is to buy a new motherboard.

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    Power Supply Causes of No Power to the Motherboard

    Sometimes the power supply is at fault for no power to the motherboard. One of the most common errors made by computer builders is failure to properly set the power supply to the correct voltage.

    Notice that there is a little red switch recessed into the back of your power supply. Using this red switch, you need to set the voltage of the power supply depending on the country in which you intend to operate your computer. The United States uses the 110/115 volt standard whereas Great Britain uses the 220/230 volt standard. Using the wrong setting can cause damage to both the power supply and any of the components in your computer. To check your country’s voltage standard, check out Voltage Valet’s Directory of Foreign Electrical Information.

    One of the problems you may encounter when buying a power supply is the industry’s focus on power supply wattage. The more components you have in your computer, the more wattage you will need to power all of these parts. Unfortunately, power supply manufacturers only tout their products’ wattage and fail to inform customers of amperes, the number of 12 volt rails within the power supply, and several other important factors. If your computer’s parts require 600-watt peak power and your power supply is just at or under this threshold, you are likely to experience intermittent problems whenever your computer tries to draw too much power.

    Before you buy a new power supply, do the math to determine your computer’s needs. Start by adding up the peak power requirements of each of your computer’s components. Pay particular attention to the most power-hungry components such as the CPU, the video card, and the hard drives. Also, be sure your power supply meets the minimum amperes requirements for the total number of components in your computer. Failure to do so may not only create power problems, it can damage the components in your computer.

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    Conclusion

    There are two main causes for a power supply failing to supply power to a motherboard: motherboard problems and power supply problems. Before you begin troubleshooting these two main causes, be sure to rule out obvious causes such as parts not being plugged in and the switch on the back of the power supply being set to “off." From there, you can troubleshoot and fix your no power to motherboard problems by following the advice discussed above.