Selecting The Right Power Supply for your Needs

The necessity of the right power supply is an often underappreciated component. When picking the right power supply, you will face an array of options. Power supplies are graded according to their efficiency, while they also have varying wattage. You’ll also have to decide on the cabling. Picking a quality power supply can mean the difference between a well running system and a system that suffers from crashes and boot failures. Even worse, cheap models can literally explode into flames, taking the rest of your computer with it.

How Much Power Do I Need?

The biggest problem power supply buyers face is how much power is actually needed.  Each system is going to have its own exclusive power specifications, but commonly it all focuses on two things: overall wattage, and rail specific power. Overall wattage simply means how much overall power a system needs in order to run properly. There are several power supply calculators available on the web that can help in determining this. Rail specific power is the measure of how much power certain components in a system draw from the power supply. This normally applies to how much power large components like graphics cards pull from the power supply’s main +12V rail. For most systems with a few low-level graphics cards, this usually isn’t much of a concern. However, builders with high-end graphics cards should refer to the manufacturer’s specifications on how much power a particular card needs, and then check if your power supply of interest is capable.


Power supplies come in all shapes and sizes and another variable to consider when choosing your power supply is what connectors it has. PSU manufacturer will normally list how many SATA, Molex, CPU power and 24 pin connectors its PSU will have. Power supplies are available with hard-wired cabling, with partially modular cabling, or with fully modular cabling. In modular power supplies, you can add or remove cabling from the PSU as needed to avoid case clutter. Technically, a power supply with hard-wired cabling is optimal because it requires no additional connections between the unit’s internal PCB and the connector that will ultimately be plugged into one of your components. Modular cabling greatly simplifies keeping the interior of your case nice and clean—just don’t connect any superfluous cables to keep the clutter down. Most people prefer modular PSUs, though they cost a bit more than non-modular models.


There is a rating system for power supplies known as 80 Plus. This rates how well a unit keeps up at 80 percent efficiency over its load range. This is measured in five stages. As a rule of thumb, higher 80 Plus ratings are more efficient power supplies and overall better quality. Another advantage of owning a PSU with a 80 Plus power supply is noise reduction, since fans don’t need to spin as fast to cool your computer. Overall an 80 Plus power supply will reduce the heat output of your computer, and will counteract the chance of your computer overheating. Preventing your power supply temperature from rising will keep your computer working at an efficient level. You also need to consider the actual physical size of the PSU you’re putting into your PC. In a huge tower-style case it might not matter, but even then, make sure you’re not blocking any drive bays by getting a gargantuan power supply you may not need. There are lots of great options that are also very small.

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