Choosing the Right Power Supply for Your Desktop

Last Edited: September 2, 2018 | Published: September 1, 2015 by

Choosing the Right Power Supply for Your Desktop

One of the most frequently ignored components of a good desktop is the power supply.  Many computer builders either mistakenly believe that more power equals better or some just ignore the power supply completely and just use whatever happens to come with their case.  Unfortunately, the power supply market is filled with manufacturers that use crappy parts and then overstate the capabilities of their hardware.

So how do you choose which one is right for you?  I know it can be tough to wade through the massive amounts of power supplies available on the market in search of creating the best desktop pc possible.  Luckily, you have us to help you.  Today we will take a look at exactly what makes a power supply good so we can help you make the right choice when the time arrives for you to buy a new one for your computer.

Why Worry About Your Power Supply

You may be sitting there wondering why you should even bother to worry about what power supply you get.  Won’t any old power supply do?  Be careful.  Every single part of your computer needs electricity in order to run, and your power supply is the component that pulls and distributes that electricity to the various components in your computer.  Without it, your computer simply can’t run.  If you buy a power supply that doesn’t control the power properly or is too weak for the components you are using, you will find that your computer will randomly crash and shut down when you least expect it.  In more extreme cases, a bad power supply can even damage some of the other more sensitive components in your machine leaving you with a potentially expensive repair bill.

Choosing a Power Supply


There are many different aspects of a power supply you need to consider before you buy it.  When deciding what power supply to buy, it is important to consider all of the factors below so you can choose the best power supply for your needs and the components inside your computer.

Watch Brand Names

Normally, I always believe that you should never buy something simply because of its name.  While I do believe this, when it comes to power supplies I think you should give a little more weight to the more popular and reliable brands out there.  With so many shoddy manufacturers, buying a power supply that isn’t a name brand or not well known could lead to problems down the road.  While the brand names are not immune to those problems, you will find that there are far less of them with those manufacturers compared to the knock off power supplies made by manufacturers that you have never heard of.

A Word About Watts

Power supply manufacturers list power supplies by their output in watts.  Typically, you will find power supplies ranging from 200 watts all the way up to 1800 watts.  Anything larger than that would exceed the load on a 15 amp electrical outlet.  The more watts a power supply has, the power it can provide your components.

Of course, figuring out how many you need can be a bit of challenge.  Typically, computer component manufacturers will list the power requirements of their components.  You can use these requirements as a guide when picking how much power you need.  The other thing that you must be aware of is load and peak efficiency.  Most power supplies hit their peak efficiency between 40% and 80% load.  Ideally, you should strive to hit between 50% and 60% efficiency when building a computer.  This should give you enough power for smooth operating as well as giving you a little room to grow if you want to add something to your desktop later.  For example, if you add up your components and they require 500 watts, then at minimum you will need a 1000 watt power supply.

One of the most common misconceptions about power supplies is that the ones that are higher in watts will use more electricity.  This is simply not the case.  The power requirements are dictated by your components not the power supply itself.  This means if you have an 1800 watt power supply connected to a computer that needs 500 watts, it will use the same power as a lower watt power supply.

Efficiency is Key

Why do you want more efficiency?  There are actually several reasons.  Power supplies with higher efficiency ratings often use much better components.  This translates into a more reliable power supply that uses less heat, wastes less power and is much quieter as the fans won’t have to run as fast to keep it cooled.

When shopping for a power supply, you should search for units with an 80 plus certification.  While this certification will add a bit of cost, when you find it you know that the power supply is much more efficient that one that didn’t earn that rating.  There are also different grades that guarantee that a power supply is even more efficient – 80 plus bronze, silver, gold, platinum, and titanium.  The higher up this list that you go, the more expensive a power supply will be.

Which one of these power supplies you choose is really up to you and your budget, of course.  If you are an average user who doesn’t want to spend a fortune on a power supply, you should shoot for the standard 80 plus rating or maybe even the 80 plus bronze rating if you are willing to stretch yourself just a little bit.  Remember, the higher the rating the less power that will be wasted, meaning it could save you a small amount on your electric bill, although the amount is probably so small you will never really notice it.

How Many Rails

How many rails your power supply have and the question if more is better has been debated for some time and continues to this day.  Basically a rail on your power supply is how many +12V rails your power supply has to deliver power to the different systems of your computer.  Some power supplies have one single rail while others divide the rails into two or even three lower powered rails.  But which one is better?

In the single rail design, all the power is fed through one single rail.  This design is, of course, much simpler compared to the multi-rail approach.  The simpler design means it is easier to connect and suffers from fewer problems compared to the other method.  The downside is if there is a failure of some sort in the power supply, it has the potentially of delivering much more current to the sensitive components in your computer.

In the multi-rail system, the power is divided up among the rails.  These rails are completely separate from each other allowing you to load balance the system.  If something goes wrong, much less power will be potentially delivered to the other hardware of your system.  However, these systems are much more complicated to setup.  You will often have to load balance the rails yourself.  If you don’t, you could overload the power supply triggering a shut down.  If you aren’t too familiar with these power supplies, you could find yourself frustrated as you try to properly balance the power hungry components in your system.

So which one is better?  From an output and functionality standpoint, neither.  Both usually work equally as well and both make great choices for powering our computer.  In reality, this choice is more up to you.  How much time do you want to spend load balancing your components just to get a little added security from power surges?  If you don’t mind dealing with it, go ahead and go multi-rail.  But if it sounds like a chore to have to do that when you setup your new machine, a single rail approach may be a much better option for you.

Modular or Hard Wired

There was a time when all a power supply was was a box with a big mass of wires connected to it.  When building machines you have to take a little extra time and invest in some wire ties to properly organize the inside of your case to keep this spaghetti of wires from blocking air flow in your machine.  Times have changed, though.  Today you can easily get what is known as modular power supplies.  These power supplies allow you to connect exactly what wires you need to the power supply so you can keep your case clear of all the extra cables and wires that you simply do not need.  So what type should you choose?

The classic power supplies are still made today.  The advantage of these is there is much less resistance on the lines as one end of the cable is soldered on.  This means that there is also less of a chance of a failure on those lines.  With modular designs, you will have far less cables to deal with but there is an increase in resistance and failure because there is an extra hop the signal must make at the connection point on the power supply.   This also increases the chance of a failure at this connection.  To be fair, however, the resistance is very low as is the chance of failure so this may not be much of a concern for you.

Personally I prefer the modular designs today as it allows you to reduce case clutter and improve the airflow to properly cool your system, which is especially important if you are designing a high end video editing or game machine that could potentially generate quite a bit of heat.

What Are Your Needs

Now that you understand some of the more technical aspects of choosing a power supply, you must understand that your needs will greatly impact the power supply you will buy.  If you are building a desktop that just needs to run basic software such as Windows and maybe the Internet, you won’t need components that are as powerful when compared to a video editing powerhouse desktop or a gaming behemoth.  So examine closely how you plan on using your computer and what components you plan on installing in your new build before you buy.  In fact, I would make the power supply the last component you select for your computer.  Once you know how you are going to use it and what components you plan on buying, you can then select a power supply that can provide enough power and stability to properly drive those components as you use them on a daily basis.


Final Thoughts

As you can see, there is much more to choosing a power supply than just picking one off the shelf or sticking with the one that comes with your case.  There are, in fact, many different factors you must consider when choosing the right power supply.  Remember, never choose a brand that you have never heard of and always look closely at the reviews before making your decision.  On top of that, be extra careful that you select a power supply that will provide you with the right amount of juice so that all the components inside your computer continue to function normally and stay free from damage that could be caused by a surging power supply.

When selecting your power supply, all you have to do is follow our list and see how each one you consider stacks up against the other.  Once you have narrowed down your choices look even more closely at its reputation and use those to help guide you when the time comes to make your final selection.  While this may seem like a bit of extra work, in the long run you will be glad you did it, as your desktop will run much more smoothly when you finally finish the build and begin using it day in and day out.

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