How to buy a power supply which ones for me.

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The power supply is arguably the most important component in every computer system. It must supply a steady, reliable source of power to every other component in the system, and it must do so without making too much heat or noise. If the power supply is incapable of providing the power needed, data corruption and possibly physical component damage could result. It is paramount, therefore, to choose a quality power supply when building a computer.

We urge you to stertch your budget as much as possible when buying PSU as it can save your ££££££ in the long run.

Compatibility & Connectors

The most important feature of a computer power supply is its compatibility. A power supply's main connection is with the motherboard, and there are now two main standards for desktop computers that must be considered. Older and less feature-rich motherboards use the 20-pin ATX connector (fig 1.1). Newer, more feature-laden motherboards use the 24-pin ATX connector (fig 1.2). Although a 24 pin power supply can be used with a 20-pin motherboard via an adapter, it is not recommended to attempt the reverse, for a 20-pin power supply was not designed to provide the necessary voltage to all those wires


20 Pin connector                                   24 Pin connector


In addition to main motherboard connectors, power supplies also differ in the other connections they offer. All power supplies have 12V molex connectors (fig 2.1) which are used to power peripherals such as CD/DVD-ROM drives, hard drives, and case fans. Make sure the power supply you are looking at offers enough molex connectors to meet all of your needs. In addition, the emergence of SATA hard drives and PCI-Express video cards means that you must make sure the power supply you are looking at provides these features if you plan on implementing them in your computer (fig 2.2 & 2.3).

Fig 2.1                                                            Fig 2.2                                                Fig 2.3


4-Pin Molex Connector                               PCI Express Connector                        Serial ATA Connector

While on the topic of connectors, it is important to discuss the rails in a PSU. All computer power supplies have three voltage rails which they are responsible for regulating: the 3.3v rail, the 5v rail, and the 12v rail. The motherboard will draw current from these three rails in varying amounts, depending on the design. Current draw is difficult to find for most components, but if possible it is a good idea to research this and make sure that your proposed power supply will be capable of powering your system. Reputable power supplies have their maximum amperage ratings for each rail printed somewhere on the unit.

A new technology called SLI has recently surfaced in the computer industry. This revolutionary concept allows a user to combine the processing power and memory of two video cards, allowing for insane performance. If you plan on using dual video cards in your 1337 gaming rig, you need to make sure the power supply you purchase is SLI Certified if you have Nvidia video cards, or ATI CrossFire Ready if you are running ATI. This will ensure that the power supply is capable of feeding not one, but two hungry video cards, and will help reduce the possibility of instability.

Power supply size

Finally, the last parameter which must be considered when purchasing a power supply is whether it will fit in the enclosure you have planned. Most power supplies conform to the ATX specification, and will work in most cases as a result. Cases with a top-mounted blowhole fan should be checked for clearance with a proposed power supply; the depth of power supplies is not standardized and could vary enough to make clearance an issue. If you are going with a small form factor or micro ATX case, make sure you have selected an SFX/Micro ATX Power Supply.

Modular and Sleeved Power supplies

After all of the necessary parameters have been considered, there are plenty of other options a consumer has at his or her disposal. Power supplies take up a fairly large portion of the space inside a case, and as such are very visible inside windowed cases. Of course, no one wants to look at ugly red and black wires everywhere, so there are a few different solutions to deal with this problem. A sleeved power supply features plastic sleeving (usually UV reactive) that surrounds the wire bundles and offers a much cleaner appearance. Modular power supplies (fig 3.1) actually sport wires which can be plugged and unplugged from the power supply unit, which means that a user only needs to install the cables he or she needs. Such modular cables are also sleeved for the ultimate aesthetic appeal. If noise is a concern, there are a number of silent power supplies which provide power without using any fans and therefore have no moving parts. Such a power supply will not be as powerful as a fan-cooled version, but to some the lack of noise is worth it.

Fig 3.1                                       Fig 3.2                                     


Modular Power Supply               Standard Power Supply         

Finally, a newcomer to the power supply scene will be at a great disadvantage without knowing which companies' products can be trusted. Luckily, such knowledge is not a trade secret and I am happy to share my thoughts. There are a number of well-established brands which can be counted on for quality and reliability we at Leftclicks UK carry a large line of computer power supplies. PC Power and Cooling offers the ultimate power supplies on the market, and customers will pay for the superlative performance with a superlative price. Xilence is a relative newcomer to the power supply industry but has had an enormous impact on the scene with its popular and powerful Crossfire product line.high value.


Be-Quiet is also a newcomer to the scene, but has acquitted itself well with the Dark Power Pro power supply ATI's official CrossFire certification for be quiet! Dark Power Pro hitting the best marks in reviews across europe. Other excellent choices include S Enermax and Antec. As long as a power supply is selected properly, a power supply from any of these companies will provide a stable source of power for years to come.


Be-Quiet Dark power Pro                                                                   Xilence Sli and Crossfire Ready



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