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How to: Choose a Power Supply Unit (PSU) for Your Gaming PC Build

This article is part of Newb Computer Build’s “How to: Build a Gaming PC” guides to choosing your PC hardware for your Gaming PC builds. The power supply unit is very important as without it nothing in your PC would run; it gives your PC the power it needs to turn on and function. When purchasing a power supply for the first time you may feel confused by what brand of power supply to buy, the wattage you need for your particular array of PC hardware, and a few other power supply dependent terms.

In this article I will start off by describing what exactly a power supply unit is, followed by some power supply unit dependent terms, and then conclude with a few steps you should follow when choosing the right powers supply unit for you.

What is a “Power Supply Unit”

The main purpose of the power supply unit aka. ‘PSU’ is to power your PC, and it serves this purpose by converting regular alternating current (AC) power into direct current (DC) power to be used by the internal hardware parts of your PC. PSU’s are generally rated by their maximum power output in Watts. A general purpose computer would use less power and would only need a PSU with a power outage of around 300W to 500W, however here we are concerned with gaming PCs, which you will most likely need a PSU with a power outage of anywhere from 450W to 1400W depending on all of the hardware you have.

A PSU will come with various connectors of which will come with a variety of the following: (From: Wikipedia)

Now for a few terms you should be familiar with when choosing a new power supply unit for your gaming PC build.

Terms you Should Know (For a PSU):

Power Supply Unit Type: This designates the type of power supply unit. For the mostpart and what we are concerned with here (for building a PC right now – especially gaming PCs!) are the ATX types of power supplies. ATX is basically a technology standard of sizing for motherboards, computer cases and power supplies.

Main Connector: This will be the main connector, the one that connects the power supply unit to your motherboard. Most likely if you are purchasing an ATX power supply unit the main connector will be a 20+4Pin connector. This connector will fit into either a 20 pin or 24 pin main connector on the motherboard.

+12V Rails: Supply supplemental power to the processor (sometimes the graphics card) on the motherboard.

PCI-Express Connector: As the name states this type of connector will power a PCI Express card such as a Graphics Card.

SATA Power Connector: The SATA power connectors will be the connectors used to power any SATA hardware. The number of SATA ports will usually vary, so you may want to check the number of SATA connectors depending on how many mass storage devices you plan on having. This is generally the number of hard drive + the number of optical drives (DVD, CD Blu-Ray etc.)

Efficiency: The efficiency rating for a power supply unit will usually be give in a percentage. What this means is the percentage of efficiency of AC currnect that will effectively be converted into DC current.

  • For example: If a power supply unit is stated as being 75% efficient and has a 750 Watt energy rating, what this means is that is takes roughly 1000 Watts of Alternating Current (AC) in order to convert to 750 Watts of Direct Current (DC). If it takes 1000 Watts of AC to convert to 750 Watts of DC power, then the excess power (250 Watts) is lost to heat.

MTBF: Is the Mean Time Between Failures – Which is the mean amount of time that passes between any inherit system failures during operation. (For example: MTBF: > 100 000 hours would mean that the inherit time between failures is 100 000 hours). This is not necessarily the most important thing you need to keep in mind when purchasing a PSU for your gaming build, but it may be something interesting to know.

Modular Power Supply Units: These are simply types of power supply units that have modular cables. This enables you to detach any cables that you do not end up using so that they don’t take up more space than they need to in your computer case. For the most part this is not ever actually required, but if you like to keep things clean and hate messy cords then you may decide to go modular. The only downside is that you will end up paying more money for a modular PSU.

How to: Steps to Choosing Your Gaming PC Power Supply Unit (PSU):

Step One: How Much Power do you Need?

Nope, I did not start with budget this time. Why? Because I believe the power supply unit should not be something you try to save a ton of bucks on; after all this is the main unit that powers every piece of hardware you have and will be purchasing. However, the main question is how much power is enough power? The actually PSU Wattage you decide to buy will be determined by the sum value of all the hardware power requirements you have decided to purchase.

There are a few ways your can go about determining how much power you need for a power supply unit for your gaming build, and there are some decent calculators to do this on the web. If you are looking for a good online calculator I would recommend the one at eXtreme Power Supply Calculator. The power supply should be the last piece of hardware you purchase for your build since you do need to know everything your PSU will be powering. As well, always buy a power supply with more than the minimum Wattage you need so that you can upgrade your gaming PC later on as well (this does not mean you should overshoot by 500Watts :P)

Step Two: Research the Brand

In my opinion you should always buy from a reputable power supply unit company. This is because you want to know that you are buying a relatively good quality PSU, and so you do not do any unforeseen harm in the future to your PC hardware. This can be done in a number of ways: Such as look up hardware reviews for “reviews on brand-X power supply units“, also look at the consumer reviews usually available at hardware retailer sites, or you can ask in any community hardware forums.

Step Three: Check the PSUs Efficiency Rating

If you want to know your PSU is as reliable as possible then you may want to buy one with an efficiency rating as high as possible. The efficiency rating as stated above simply is the amount of Alternating Current that actually gets converted into Direct Current for your PC, while the excess energy gets converted into heat. A poor efficiency rating may create allot of wasted heat, and would require much more cooling.

There is actually an initiative that was set place to promote more efficient power supplies labelled 80 PLUS certified. So if you are purchasing a power supply unit that says it is 80 PLUS certified you can be sure that it has an efficiency level of…well..80% and above.


Choosing a new power supply can be complicated as you do need to know everything you are either purchasing or already have in your PC, which means this should always be the last piece of hardware you decide on. Generally gaming PCs will require a power supply unit with higher power ratings as they usually have more powerful hardware such as graphics cards.

If you have any questions about purchasing your new power supply unit, or if you have any recommendations for good quality power supplies available then please leave your comments below!

And now finally, if you are interested in in building a Gaming PC please check out Newb Computer Build’s Gaming PC Builds of the Month.

OR if you need help choosing more hardware for your gaming PC build check out How to: Build a Gaming PC

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