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Understanding pc motherboard Power supplies
The power supply is an important part of your pc. But there is a bit more to it than just taking the current from your wall socket to your PC. The purpose of the power supply is to actually convert the 110-volt or 220-volt AC voltage into DC voltage for the different components parts of the pc. The reason the power supply unit has its own case, is becuase there are electrical power conversions taking place inside the power supply. The DC voltages include 3.3 volts, +5 volts, –5 volts, +12 volts, and –12 volts. The rating of the power supply unit is given in watts, which is a measure of the power.
The higher the power rating, the more power the supply can give to different parts of the computer. Most of the power supplies you will find inside a pc come in the range of a 250- to 500-watt rating. The +3.3 volts and +5 volts DC supply was first used in ATX motherboards that supported soft power off functions.
Its a good idea if you plan to take apart your pc, and change or fix any components. Plus you shouldn't be intimidated, its actually very easy once you understand what all the wires do. Its also extremely difficult to plug the power parts into the wrong place or the wrong way around. They have all been designed with the noob in mind.
Different power supply connectors
There are several different types of power supply connectors used on computer motherboards and peripherals.
Floppy drive power connector
This is a small flat connector that has four pins. The floppy connector has 4 wires and supplies 5 volts via the (red wire) and 12 volts (yellow wire) DC to the floppy drive. The connector is polarized and can only be connected in the right orientation. There is a little plastic lip normally that stops you from connecting it upside down.
Molex connectors for peripherals
The larger components inside your PC such as the hard drive and CD/DVD/Bluray drive use a 4-pin Molex connector for the power supply. The connector is bigger than the floppy drive power connector, and there is normally at least 3 or 4 that are on the testicles of your power supply. You could try and fit it in the wrong way, but it is made with a certain circular curve on two corners that means you can't go wrong.
AT motherboard power connector
This is the connector that actually gives power to the motherboard. It is normally made up from a pair of two connectors with six pins each. The connectors have small tabs on them so that they can be securely attached with a strong push to the motherboard connector. If you are removing the connector to change motherboard, you will have to lift back this little plastic clip. Its mostly found on older motherboards that don't have new up to date power saving settings.
ATX power connector
The ATX power connector is for supplying power to ATX motherboards. It is also known as the ATX System Connector. This is a single 20-pin connector that supplies six different types of voltages to the ATX motherboard. The shape of the connector is rectangular in and has a small plastic clip that secures the connector on the motherboard.
SATA power connector
One of the newest additions to everyday pc's are the sata drives for hard disks. The Serial ATA device use a 15-pin power supply connector. This connector supplies three sets of DC power, for +3.3 volts, +5 volts, and +12 volts. They have a distinctive black L shape connector, and normally a tough red plastic wire covering. You couldn't plug this in wrong if your life depended on it.