Important Factors You Need to Know When Buying a Power Supply

File-It-Under: Hardware buying!~
By: D.F.Skinner!~

The power supply unit is without doubt the most important component within every computer system,be it desktop and laptops.It supply's a steady stream of reliable power to every working hardware within your system,without system over heating or frequency interference,data corruption.To put everything in a nutshell,you basically have no computer without the power supply.In this entry we will focus on the desktop power supply,whether you are buying a power supply for a new computer or replacing a old unit,I will give you tips on how to purchase the right PSU.

This is my Antec 650 Watt power supply

The Type of Computer System
One the biggest mistakes a lot of system owners make is buying the wrong type of power supply.Wrong type you might ask,yes,wrong type in terms of wattage.If you are putting together a basic system or replacing a power supply where the system isn't a high end computer then you'er more than likely should get a 500 watt power supply,a 500 watt power supply unit is more than sufficient for low to mid-range computer.Now if you are dealing with a system where you have some heavy duty hardware that includes a high end graphic card or more than one hard drive,then you would definitely need a power supply that has a little bit more juice at minimum 600 watts.Power supply's can go all the way up to 1000 watts,though you more than likely see that type of power supply in high end gaming machines that uses heavy duty hardware.

ATX 24 pin connector that powers up the motherboard

Compatibility and Connectors
Probably the most important feature of any system's power supply is its compatibility.The desktop power supply has two main standardized connection to the motherboard that you should consider.Motherboards of yesteryear (Older) used a 20-pin ATX connector.Newer motherboards rich in features use a 24-pin ATX connector which supply's more voltage to the motherboard.In addition to the motherboards main connectors,the power supply differ in other connections.All power supplies have 12V moloex connector that is used to power up the peripherals such as the CD/DVD-ROM drives, hard drives, and fans.With SATA( Serial ATA) being the standard and dominate technology for drives,you more likely won't use the 12V connector,unless off course you need it to add fans to your computer case.

4-pin Molex connector on the right/ SATA connector on the left

There is a new technology that has become very popular with high end systems called SLI (Scalable Link Interface) . This new age concept allow system owners to combine the processing power and memory to run two video graphic cards at the same time.This type of setup requires that your power supply is SLI certified if you are running Nvidia graphic cards,or with ATI video cards ATI CrossFire certified.

These are all the wattage ratings on the side of the power supply

Knowing Wattage Rating
The wattage on all power supplies can be a bit deceptive,this is a total combination of wattage of all the available voltage lines.With increased demand by components,the total  required output by particular +12V lines become the focal point.An ideal power supply should have at best a 18A on a +12V line.The actual load you'll need depends partly on the components within your system.

This a temperature controlled large fan that runs very quiet

Absence of sound
Power supplies in whole can generate a lot noise from fans that is used to keep the unit from overheating.If you don't want a power supply that sounds like a Boeing 747 jet engine,there are numerous options available.Your best bet is either choose a unit that uses a larger fan that pushes more air through the unit at slower speeds or,purchase a unit with a temperature controlled fan which is what I'm currently using in my computer system.Another option is a fanless,silent power supply that generates no sound,the problem you have with silent power supplies is you have to make sure your computer case is well ventilated with proper air flow.

Power Efficient Rating
This is probably the most important factor when buying power supplies,yet it is also the most overlooked.Power supplies convert from wall outlets to lower levels so that your computer won't fry.During this conversion,there will be some lost of power with heat dissipation.The efficiency level of the computer determines how much power is put into the unit to operate your computer.By getting a more efficient power supply,you end up saving lots of money through the use of less overall electricity.How can you tell if your power supply is efficient,look for any unit that has the 80Plus logo showing that it has passed certification.

Mean Time Before Failures ( MTBF)
MTBF is the rating that's given by manufacturer's for the typical amount of usage a unit have before a possible failure.It is estimated that 50% of units fail and 50% live longer.The higher the MTBF rating,the better quality of the power supply.If possible  avoid any units with ratings that fall below 20,000 which equates to 2.25 years of continuous usage.You want to get at least 5-6 years usage out of your power supply.

Avoid the Bargain Basement Power Supply
Today you can get a real good quality power supply for $80,even a 600 watt name brand unit.There are still $50 and below power supply units still floating around ready to be sold,avoid it at all cost. Bargain basement units will certainly not meet the power requirements of the latest hardware.While it may power your system,you're more than likely experience system instability which can lead to permanent damage to your computer.