Axiz outlines four steps for choosing the best power supply

Buying chassis components such as a CPU, motherboard or graphics card is easy in comparison to choosing a power supply unit (PSU). Mostly due to its relatively dull exterior, very little is known about PSUs. According to Axiz, the leading IT infrastructure distributor, most users make uninformed purchases when it comes to the PSU, sacrificing PSU output for more memory or a larger capacity hard disk drive (HDD). This results in random resets, hanging and premature PSU failure.

David Ah-Tow, desktop chassis and HDD product manager at Axiz, says there are four key areas to consider before purchasing a power supply:

1. Form factors which include ATX and BTX
2. The cooling process of the PC
3. Stability
4. Power

According to Ah-Tow, most users are unsure about how much power is required for a system and will therefore purchase mid-range components and house them in a chassis powered by an entry-level PSU.

"A balance needs to be found between the components desired and the actual required PSU output required. These four steps should enable the PC user to make an educated decision when selecting a PSU."

Of the many form factors available to the IT market, including the recently introduced BTX form factor, the ATX form factor is widely used and found at most computing stores. ATX-powered chassis were introduced in 1995 and have since undergone two significant upgrades: ATX12V and ATX12V V2.2. In instances where the BTX chassis required is micro-BTX or Std-BTX, the ATX and BTX form factors will share the same power supply. Other form factors can be found at www.formfactors.org.

The power supply plays an integral role in the cooling process of a PC by using its own fan to assist with the extraction of air that has been heated by the system components. The noise generated by the extraction process is often an issue for users. To overcome this, some manufacturers have introduced a variable fan rotation speed feature whereby the PSU`s fan speed is increased or decreased, depending on the load it is carrying.

The heat generated by the components is extracted by the PSU fan and chassis fans that are located in the front and rear of the system respectively. As temperatures return to normal, the fan on the inside of the PSU slows down. A variety of chassis fan sizes and quantities are used in PSUs today. The single 80mm fan is the norm for most entry-level PSUs. Mid to high-end PSUs will use either two 80mm or a single 120mm fan, (the 120mm fan scoops more air due to its longer and wider blades). The fan will then run at a slower speed resulting in less noise.

A high-quality power supply, but not necessarily one in the high-end category, ensures stable output voltages. This stability is important to consider because it helps maintain steady voltage outputs when fluctuations occur in the actual mains supply, or as a result of varying consumption needs from any of the computer`s components.

Power supplies are classified according to maximum output power, measured in watts. The larger the power supply capacity, the greater the number of components, or the higher the number of components that can be supported by the PSU. A good quality power supply, which provides 300W of true output, can power an entry-level PC without experiencing problems such as random reboots or premature PSU failure as a result of overstrain. Manufactures recommend between 400-500W for any mid-range to high-end system.

"Users need to plan ahead and take cognisance of the fact that the required power consumption quoted for components continues to climb. However, it`s rare to have every component drawing full power constantly. It is also preferable not to run the PSU at 100% capacity continuously," says Ah-Tow.

When purchasing a PSU, its capacity should always exceed the requirements of the components in the PC.

"A PSU that far supersedes the needs of the components it powers is ideal."

According to Ah-Tow, this provides peace-of-mind for the end-user by giving them the confidence that the PSU will cope with most hardware upgrades in the future.

"Too many individuals don`t consider the PSU when buying computer equipment. Nor do they realise that it is the backbone of the entire supply of power to a system, irrespective of the number of components. A balance must be sought to avoid unnecessary warranty claims and related issues."

For more information, contact Axiz on (011) 237 7000.