This series of articles has two purposes at the same time: educational and commercial. They will try to explain as clearly as they are what the various PC components are and at the same time they will guide you in choosing the best components for your purposes.

PSU schematic
A computer needs energy. To do this, we use power supplies, also known as PSUs from their English abbreviation. Their task is to extract alternating electrical power from the socket in their home and convert it into direct current at different voltages to power the electrical circuits.

Watt: The Watts represent the electrical power that the power supply is able to supply to the output, that is to the components inside the computer. It is very important to distinguish between the peak current and the continuous current. A power supply from 800W peak, will be able to support this value only for a few seconds, while a power supply indicating 800W continues, will be able to support them indefinitely. The important thing is to ensure that your power supply has enough power to guarantee power to the whole system when it is in maximum load conditions.

Efficiency: The quality of the internal components of a power supply determines the energy efficiency. To do this we use a nomenclature called 80 PLUS, which uses a medal system, starting from without a medal, to go on bronze, silver, gold, platinum and titanium. The lower step ensures 80% efficiency at 20%, 50% and 100% of its nominal load, while the higher one exceeds 90%. Efficiency determines the actual consumption of your power supply. If you are asking 328W on a power supply with 85% efficiency, you will be measuring 385W on the wall, ie the socket, with 57W dissipated in heat.

Load curve: Each power supply has its own load curve, which measures its efficiency in correspondence with the% of load required. In principle, the maximum efficiency of a power supply is at 50% of the load, while at low loads the efficiency is very bad. At high loads some points are lost with respect to the middle line. Thus, a power supply from 500W, will have its peak of maximum efficiency at 250W. It is not a factor that comes into play when choosing which power supply to buy, but it is convenient to know.

Modularity: The power supplies can be modular or not. This indicates the cable layout. A non-modular power supply will have power cables all attached to its body and cannot be separated. A modular, it will have the user-insertable cables. The difference between the two is mainly of aesthetics and ease of assembly. There are semi-modular feeders that are something in between.

Form format: The feeders can be of various shapes. The standard dimensions are those of the ATX format. The different abbreviations are generally used to indicate smaller formats. We therefore have SFX, which is very popular because it is slightly smaller than ATX, TFX, PS3 and others less used.

Rail: A power supply can have more or less lanes where to run the electricity. The most important supply line is the one from 12Volt, since it must supply the CPU and the GPU. If a power supply has only one rail, all the current will pass on the same road, being protected by a single system. A multi-rail power supply instead will divide the load on its roads. This approach guarantees greater safety and reliability.

The market

PSU components close up

Building a power supply is something relatively simple. Standard and common electronic components can be used, electronic boards, copper, transistors and tacs, a power supply has been made. The problem is to do them well, able to last and ensure a clean and stable output supply. For this there are many manufacturers of power supplies, but there is a great variation in quality between them.

How to choose

NEVER save on a power supply. It is the most important component for a PC and, without him, the other pieces cannot even work. That being said, it is not even necessary to spend capital on it. To understand how many Watts my system needs, you can use the span system which I really like. Take the TDP value of your CPU, add it to your GPU, add 50W and multiply by 1,3. You will get an indicative value of your PSU. Today's electronic components, when used correctly, rarely consume more than 500 watts. If you overclock very hard, or want to use dual GPU set-ups (however unwise) it is often necessary to go beyond 700W.

Shopping tips

PSU Economic, but good

These models, and their relatives of different wattage, are excellent economic options. Dispassionate advice: avoid power supplies that cost significantly less if you are building a gaming or work system that needs power.

I want a quality power supply

The carousel feeders above are sorted by actual quality, with the Be Quiet! Dark Power Pro 11 at the top. They are modular or semi-modular mixed. Solutions with Watts "at random" are indicated, following the above formula or calculating with more precision, you can recover the models with the same identical name, but different Watts according to the needs.

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