Computer Power Supply – The Key Component of the PC

A computer power supply is the most important constituent of the computer. Without it, a computer is a merely a plastic box with some metal & silicone thrown in. The function of computer power supplies is to convert the alternating current of your home line to direct current. A computer requires direct current for its working. You can find the power supply, a metal box, in the upper back of the computer case. You can also locate it by the power cord receptacle going to the back of the case.


An computer power supply is known technically as a field replaceable unit (FRU) the reason it’s called this is because during a power surge the supply is built to “sacrifice” itself and burn out. Therefore saving your precious inner workings of your PC. Power supplies are hardly ever repaired because they are so cheap they can then be replaced with a new one.

Computer power supplies are also known as “switching power supplies” or “power conditioners” as they use switcher technology for changing alternating current from your home or business to direct current that the logic circuits your computer requires. The different voltages supplied are 3.3 volts, 5 volts and 12 volts. The 3.3 and 5 volts are generally for digital circuits. Disk drivers and fans use 12 volts. The power supply is in watts.


Computer power supplies before the eighties were very bulky with the AT standard. Huge transformers and capacitors were used to change voltage (120 volts and 60 hertz) into DC (5 volts and 12 volts). Nowadays, the switching power supply is small and light. The supply converts the 60-hertz current to a higher frequency. A small transformer step downs the voltage from 110 volts to the voltage required by the PC. The switcher supply provides the high frequency AC current. This current is much easier to filter and correct as compared to the 60 hertz AC line, which reduces the voltage difference for the sensitive computer components.


With about six different standard power supplies for computers, the need for standardization arose. ATX is the computer power supplies standard. ATX is a specification dictated by the industry that tells that the power supply has the physical attributes to fit in a typical ATX case and the electrical attributes to work with the motherboard of ATX. To keep the wrong ones away, the computers power supply cables are also standardized. As a consumer, you have many choices for replacement of the power supply as color-coded wires and standard connectors are available.

Computer Power Supply   The Key Component of the PC

Energy Efficient

The Computer power supplies should be of high quality with the capacity to fulfill your systems demands. A poor quality supply can lead to system crash or may develop bad sectors on the hard drive etc. Secondly, the supply should have proper cooling and should be energy efficient. The new energy saving PC power supplies cut back on the energy consumed by the system when it is not busy. The supply should have the provision to give the system more power when it needs more power and when the system power requirement is less, give less power. The energy efficiency and saving here can sum up to huge energy savings. Consider the upgrade capacity of the supply, as this will determine how many new drives you can add or upgrade to a better motherboard. Do not try to save cost by buying a low quality power supply; it will do more harm than good in the long run. The power factor should be at least sixty to seventy percent and do not forget about the warranty.

It should also be noted that the new power supplies coming on the market are modular in style. For decades, the supply came with all the wires needed for that current days technology whether YOU needed them or not. With so much hub-bub about case modding, the new modular power supplies allow you to only attach the cables you need for the components you have. No more bundle of ugly wire taking up needed cooling space in your case. You only use the wires you need.

Power It Up

A computer power supply requires greater power if your system has all the slots or drive bay on the CPU. A graphics card may need 20W to 30W; PCI card needs 5W while a SCSI card needs 20W to 25W. A floppy drive requires 5W but CD-ROM drive needs 10 to 25W. Thus, the requirements differ from component to component and system to system.

The major manufacturers of computer power supplies are Antec, Aspire, Coolmax, Inwin, Raidmax, Rosewill, OCZ, Thermaltake, Sparkle, Ultra,Vantec, Zalman and others.