For those of you who know nothing about PSUs, today we're taking it from the top. The abbreviation PSU stands for power supply unit, and in this article, we assume that it is also an SMPS (switching mode power supply), since in modern PCs only SMPS units are used.
You can think of the PSU as the heart of a PC; it is the most significant part of the system since it feeds power to the other components, including the CPU, graphics card, hard drive, SSD and so on. If the PSU fails, it affects all of the other pieces. And in some cases, a malfunction of the PSU can damage other components as well, especially if the PSU is of low quality with inefficient protection features. Unfortunately, this is something many builders ignore. Instead of choosing an adequate PSU for their systems, users typically acquire all of the other components first, using leftover funds for the power supply purchase. If you've made this mistake, we are sure that after reading this article you will change your PC building strategy. However, this article is not just intended for novice users and goes beyond the basics of PSUs, providing valuable information to experienced enthusiasts as well.
In the following sections we will provide an easy-to-follow explanation of the switch power conversion. We will also make a brief reference to the most significant electronic components currently used not only in PSU manufacturing, but also in every modern electronics device. Through the following pages you will learn the basic concepts of inductors, capacitors, resistors (see resistor color codes), transistors and diodes in order to better understand PSU components. Next, the main context of switching power conversion will be explained and a brief description of the various stages that compose a PSU will be made. Afterward, we will make a brief reference to some switching regulator topologies, which are commonly used nowadays. Some of you might not be aware of this, but a PSU's cooling fan is usually the first part to stop working, at least in good-quality PSUs, so we will dedicate some time to discussing cooling fans as well. Next, we'll spend some time on protection features, and finally we will take a look at ATX, EPS and 80 PLUS specifications.
This is going to be an informative journey through electronics, and when you finish reading this article, we are confident that you will have gained valuable knowledge that will help you to better understand the "Look Inside" pages in our PSU reviews. In addition, you will be able to judge the technical specifications of a PSU by yourself.
In the following section, we briefly describe the most significant electronic parts that are used in PSUs, including inductors, transformers, capacitors, resistors, transistors and diodes. This essential knowledge will help you when we analyze the internal parts of an SMPS, especially if you don't have an electronics background.
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Power Supplies in the Forums
Cornell Dubilier (USA)
Illinois Capacitor (Now owned my Cornell Dubilier)
Kemet Corporation (USA)
EPCOS (TDK company) (Germany)
Würth Elektronik (Germany)
The other brands are mostly found in specialty applications such as lab instruments, industrial machines and high-end audio.
I basically have committed PC heresy with my cx600m. However I think that I'm in the clear with my 65w CPU and 145w CPU. I'd bet my total power draw is actually below 300w, the supposed highest efficiency point of a PSU.
As a gamer, not a professional, I think it is better to get low power parts, and get a higher rating than you need, rather than get high power parts and high quality PSUs.
Additionally, if you compare power consumption of a typical system from today to one from 5 years ago, power draw is considerably lower, with the exception of certain graphics cards. *cough* 390x *cough*
Thanks Aris for this very useful article on behalf of us all who want to learn the basic knowledge for PSUs.
Haven't finished it yet, but i'm very anxious for it !!!
PSU and MB are insignificant to me and I can blindly pick one by reviewing user comments from newegg in about 5 min, and it will last for years. For less than $100 each I'm set for nearly a decade.
CPU and gfx card now that affects fps and is over $1000, actually the most important part to me.
I heartily dissagree, user are not the best way to judge reliability, and a bad powersupply is at fult most of the time there is a hardware issue. Further a power supply should last more than one system build, and in general I keep mine for a decade at a time at least. So an investment in a good power supply is not a waste, and a bad one will kill that precious $1000 GPU or CPU. The demo dart power supply on the motherboard is a similar story, however in general they are of higher quality than a cheap mains supply.
As well as SMT ceramic capacitors, Kemet makes through hole aluminium electrolytic capacitors. These are of high quality, though not as well known as their SMT capacitors. They also make high quality polymer SMT capacitors that are used as bulk capacitors on the power distribution circuitry on laptops and other devices.