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Power Supplies

Power Supplies

Although it might look like its a regular unnecessary box, power supply is a very important part of your computer. Bad power supply can mess up all your internal computer hardware. Want to learn more about power supplies? Read full article...
So what exactly is a Power Supply?
Power Supplies

The Power Supply, also known as PSU, is a box that delivers power to all your internal computer hardware parts. If you compare computer to a human body, PSU does what heart does in a human body. It delivers needed power to internal parts, such as motherboard, processor, hard drives, dvd drives, RAM memory, video cards, etc. The power supply also converts 110v/220v into computer's 12v, from AC to DC. Remember, do not underestimate a power supply.

I had experience with good and bad quality power supplies. Do not get a cheap made and low price power supply. Sooner or later, problems may arise. Bad power supply can cause dead screen (blue screen), can cause computer to randomly restart itself, can defect some or all of your internal computer hardware, and worst of all, can burn down your house.

We'll cover all types of power supplies out there and at the end of the article, you can always ask a question and I'll do my best to help you.


You probably have seen different computer cases, some of them are huge and some of them are tiny. Common sense will tell you that they all use different forms of power supplies. We will cover all common form factors and you'll have to decide which one to get, keep in mind that its not only about size of your computer case, but also about functionality of the power supply.

ATX - ATX power supplies are pretty much out of business. You don't even have to read this paragraph as it will be even hard to find power supply like this on sale. It definitely lacks power and there is no way you'll need to buy it for a gaming pc. Even if you will find it somewhere, may be in a garage sale, prices of these power supplies are about the same as ATX 12v, which we'll cover in the next paragraph.

ATX12V - This is what you probably need to get if you build a regular average computer for office use. You might be wondering what's the difference between ATX12V and ATX. Well, to say it simply, the additional power for your processor. Speaking of which, be sure your processor is compatible with your power supply. Either do research online, ask here, or simply get latest power supply type. ATX12V have the same dimensions as an ATX power supply.

EPS12V - Comes with 8-pin CPU power connector with 4-pin connector. This form was originally made for servers, but nowadays it is somewhat popular in high end computers. Once again, if you are interested in this power supply, make sure your motherboard will support it. Once again, ask questions.

SFF - These power supplies were made for small computers. You'll need to worry about those only if you decide to build a light and small computer. It is tougher to find power supplies like that, especially for a gaming computer.

Now, you probably decided that its time to buy power supply. You know the size of your computer case, you made sure the power supply will work with your motherboard, and about to go online and make purchase. But hold on, do you know what to look for in power supplies?

Power - Don't you ever, and I repeat, don't you ever make your decision on buying power supply by looking at maximum power label. You have to do more research. Even though it might give you basic idea on what you can power with that supply, look under +12 rails. If you are building regular average office use PC, 25A should be fine. If you want to play some games once in a while and work on some video editing applications, go with over 40A. If you building a hardcore gaming machine, go over 60A.

Power Supplies

Now you probably still wondering, what amount of watts to get? I wouldn't buy anything under 500W. Keep in mind though, get a good brand, do some research, read user reviews before buying a power supply. Found one you like? Ask here, leave a comment, and I'll let you know what I think.

If you didn't know yet, there is a big difference between continuous and peak power. Continuous is a stable power your power supply delivers. Usually the maximum power of the power supply label is the continuous power. Peak power is maximum power the PSU (power supply) can deliver. It may deliver couple hundred watts more, but only for a really short time, example would be 10 seconds.

Connectors - Whenever you buy a power supply, look at what connectors it has and compare it with what connectors you need. Most important connector you need is the main power connector. Now, remember, you need 24-pin connector, if you get an old power supply, it might still have 20-pin main connector, but most new computers, motherboards, power supplies, use 24-pin connector. Besides, if your motherboard needs 20-pin connector, your 24-pin connector from power supply will work just fine. If you are using old motherboard, just get a 20+4 pin connector. It will work great.

Power Supplies

The main power connector connects to the motherboard. You can't miss it. You'll see a huge (usually vertical) slot for the connector. Just plug it there.

If you did not read this article before you bought your power supply and it comes with only 20-pin connector, there are options out there. You can buy a power connector converter and just use that. Just look at the pictures.

If you are getting new power supply with good reviews, you should have all needed connectors, but let's review connectors you may need.

Another connector you really need is PCIe connector, which is used for a video card. I would recommend getting a power supply with at least two PCIe connectors (6-pin) because there are good number of video cards that require two connectors to be plugged in.

Power Supplies

Molex connector is a 4-pin connector, it was useful before for hard drives and dvd drives, but now you need to use SATA for that. Now I use Molex connectors only for connecting additional computer fans.

Power Supplies

SATA connectors is what you need for hard drives and dvd drives. Be sure your power supply will have enough of those to power up all your devices.

Power Supplies

Other connectors you will encounter is small 3-pin or 4-pin connector, which is mainly used to power up fans and CPU fan.

Next part is power supply efficiency. If you get a basic small computer with about 300W, its nothing really to worry about, but how about powering gaming rig at 700W and up? You might want to find a power efficient power supply.

This part is important as it will save some energy bills. Make sure you look in specs for power efficiency and the higher percentage, the better it is. I would go at least over 95%. Lets say you find a random 70% efficient power supply. If you are using 500W, your power supply will take about 700W from your power plug. You can see that you could save a good amount of money by using high efficient power supply.

Keep in mind that it also means your power supply will produce less heat, which means your power supply should last longer.

That should cover most of it. Now you should know what to look for in a power supply and what to do to make sure it will fit right in. Sometimes I had people asking me whether they should get fanless power supply that is working with heatsink, get one fan power supply, or two fan power supply. Here is my answer to that. If you are building computer only for office use, no gaming, and no video editing applications, you can get a fanless power supply. If you play games once in a while and play only basic entry level games, go with one fan. If its anything else, definitely get dual fan power supply. Whenever you make a purchase, make sure you get a quiet fan. It is measured by RPM. I would recommend getting power supply with big fan, for example 120mm. Some power supplies comes with automatic speed adjustment, which works in correspondence to the power supply temperature.

Power Supplies

Another option to consider is support for two video cards. Some gamers like to have two video cards installed on a system. My personal opinion is that it's waste of money and energy, but if you decided to go for it, be sure your motherboard supports it. Also, keep in mind that you need a pretty powerful power supply to support two video cards including good number of PCIe connectors.

When you getting a power supply, just look for a label CrossFire and/or SLI certified.

People that like to have a clean looking case (inside) are looking for a Modular Cabling. My opinion on that is simple, if price is not an issue, go with modular cabling. If you can't afford one, just get one with regular cables. You can use zip ties and secure all remaining and not needed cables. There are two advantages of modular cabling, first is inside of your case will have much cleaner look and second is the airflow. Airflow inside your computer will be improved as extra cables will not block airways.

Overload/Over-current/Over-voltage Protection would be most important of additional options for your power supply, especially if you live in an area with good amount of thunderstorms and/or floods. This can not only save your computer, but also save your house (from burning).

Well that is it. I recommend Newegg store (banner on my site) for power supplies since they are just awesome. You get great price, fast shipping, and super customer service. They also did inspire me in publishing the article. All computers I built, I used newegg to purchase all the hardware and I recommend you do the same.

Once again, if you have ANY questions, post it here in comments and I'll get back to you.

P.S. This article is for informational purposes only. I am not liable to any damage you cause to your computer, your house, your life, or anyone/anything else.

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