The Power Supply Unit (PSU) is the only thing that stands between your precious CPU and 220/110 volts of jolting electric power. In some ways, it’s like a farm mill, converting alternating current (AC) to a more PC-consumable juice called direct current (DC); the same juice that flows to your motherboard, video card, hard drive and PC monitor. A good PSU can actually prolong your PC’s lifespan and will prevent your CPU from not sounding like an airplane engine from hell.

However, being integral parts of the CPU that they are, PSUs never get the attention they deserve from people who are far too concerned with buying the chips with the highest “GBs”. If you’re not one of those people, you’ll read on.

Choosing your Power Supply Unit

While knowing the right amount of maximum power for your PC is a great way to start, it still pays to look at a power supply’s other attributes:

Maximum Power

CPUs that work harder will need more juice. Higher-end motherboards and video cards and external devices connected to your PCs take extra power, which is why one must choose a PSU that suits the load of the CPU. A 400-W PSU will be best for casual users at home or in office. People who are involved in post production or those that store a lot of multimedia in large storage devices will greatly benefit in 450-W power supply. Hardcore gamers, on the other hand, will need the most power---a minimum of 500W is required from a SLI/CrossFire compliant PSU.

Power Efficiency

Ideally, your computer should consume all the power that is fed to it. However, as the PSU converts AC to DC, some of the power gets “lost in translation”, so to speak, and becomes heat instead of usable juice. This results in a computer consuming more power than it really needs to, which directly translates to higher electric bills. So how to spot an efficient power supply? Look for the “80Plus” logo. PSUs which are 80Plus-certified are simply those that are able to convert 80% or more of the original AC power that it gets. PSUs with Power Factor Correction or PFC are also usually more efficient than those that don’t.

An efficient PSU will not only save you money on your electric bills, it will also help in prolonging your CPU’s lifespan. With more efficiency comes less heat generated; less heat means less potential damage to your components as well as less noise from the fan because it doesn’t have to work harder.

Number and Type of Connectors

The object here is to find a PSU that has the sufficient number and combination connector types that matches the needs of your CPU. A motherboard can either require a 20- or a 24-pin connector while the other parts may need a 4-pin ATX 12V, 4-pin Molex, 6-pin PCI-Express graphics and/or an 8-pin PCI-Express graphics.

For less clutter and better air circulation inside your CPU, you may opt to buy a modular PSU instead. This type only has a main power and a processor power cable and for all the other connections, has several power sockets instead of cables so that you can customize it to match the needs of a certain CPU assembly. They’ll cost a little bit more than the average PSU, of course.

MTBF rating

The Mean Time Before Failures (MTBF) Rating is simply the PSU’s expiry date, but instead of an actual date, in gives an estimated number of hours. PSU’s with an MTBF rating of 20,000 hours below translates to a lifespan of just a little over two years, so buyers must steer clear from them . This is, of course, an estimate to give you an idea of how long the device will last under the best conditions. Proper care will be your end of the bargain.

Noise and Fans

As mentioned above, PSUs, in general, generate heat and it is the fan’s job to cool it down. However, where there moving parts, there’s noise, and sometimes, more than what anyone could ever wish for. People who want to use their PCs in peace may opt to buy power supplies with fans that have longer blades and lower rotations per minute (RPM). Some temperature-sensitive fans are also available so that they don’t sound like grinding machines all the time. However, if you plan to use your PC on a well- airconditioned room and that your CPU has excellent air circulation, there are fanless power supplies out there that’re virtually without noise.

Overvoltage / Overload / Overcurrent Protection

A sudden surge in voltage, power or current may damage the components of your PC. When this occurs, this feature acts like a power fuse, automatically shutting down the PSU.