How does the power supply

We have said that the power supply use a technology called ” switching” . the principle on which it is based is that the processors ( the devices that thanks to two coils of copper wire and a magnetic core allow you to change the voltage of a voltage ) work very better , or more efficiently , if the alternating current that passes through them has a very high frequency.

Thousands of times higher than that typical of the network, which is 50 Hz In the power supplies for the computer, then , the input current is first made ​​continuous a filter and a group of capacitors, is then passed to an oscillator that transforms it into un’alternata high frequency ( a few hundred of kHz ) , at which point the signal enters a small transformer that lowers the voltage at the levels required , and finally is passed through a stabilization circuit . hence out typically 5 different voltages , plus the Mass : 12, 5, 3.3 V positive ; 5:12 V negative . The main voltage , the one that feeds the most circuits , is that at 12 V positive .

Precisely for this reason, it is necessary that output from the supply as much of the possible power on this line. since build circuits with high supply capacity is expensive , many manufacturers prefer to design power supplies with multiple output circuits 12 V. It’s not exactly like having a single line to high power , but less than the special cases end result is the same.

connection cables

The connectors power supply

answersModern power supplies have a large number of cables and connectors out. We find multicore cable to the motherboard (20 or 24-pin), one per processor Pentium IV or Subsequent (4 poles ATX12) or dual-processor card (8-pin EPS), and the 6 or 8 pole PCI-e (graphics cards in particular), and those for mass storage devices, IDE or SATA.

All about the various PC power supply cables and connectors site



one answersConnector for motherboard, 20/24 poles (separable to be used also on motherboards of old type)


two answers

8-pin EPS connector card dual processor motherboards


threee answers

Connector 4-pole for hard disks and Mass Storage IDE type


four answers4-pin ATX12V for a food processor Pentium IV or higher


five answersConnector for power supply additional PCI cards 6/8 pole (separable)


six answersConnector for hard drives and memory mass type SATA




 term indicates

On one side of the power supply label is affixed to the main features appliance. It contains most of the data we need to understand if this is the right device for your PC. Here is the information you can get.

one answersThis term indicates that the row below shows the data of the input current (mains)


two answers
Permissible voltage range


threee answers
Consumption in amps (intensity of the input current)


four answers
Frequency range allowed (in Italy the network is 50 Hz with 10% tolerance)


five answers


This term indicates that the underlying data refer to the current outgoing feeder
six answers
This line shows the output voltages of each branch in the power supply. The more powerful models can have more than one branch at 12 V


seven answersIn this line, find the maximum load (in amps) for each branch of power



In case some of the branches are interdependent (in this case the 3.3 and 5 V positive) here found the total wattage available to the sum of the branches in question


Finally, this is the maximum power rating. Although the sum of the individual classes you get a higher figure, in fact this is the real limit of the device


For those who have special needs in terms of connectors and output power, but wants a simple product and reliable despite a very low price (28,90 €), the Nilox NX-PSNI4001 may represent the power supply ideal. With a rated power 400 W, has a fan 12 cm silent type (30 dB) connector to the motherboard 20 +4 pin, 4 connectors for IDE and two SATA. It also has the ATX12V connector for CPU new generation. The PFC circuit is of passive type and the device is fully protected against short circuit, overloading and overheating.Power supply

Anyone looking for a powerful and environmentally friendly power supply, but do not want to ruin economically can take a look at GTP770 of TechSolo. Sold at 59.90 euro, higher efficiency of 82% and a total output power of 770 W. The unit has a fan 14 cm and has dual ATX12V connector, of 6 connectors for ATA disks and 4 for SATA drives. There is also a connector 6 +2 pin PCI-e card.

Who needs the silent must Consult a feeder type “fanless”. Models such as this (Fortron Zen) have generally a slightly higher cost models of equal power cooled by fan, but are irreplaceable in applications such as home Theater. The Fortron is still a proven model, that costs less than € 100 and provides about 300 real watts (80plus certified). It has ATX12V connector, 5 connectors for disks SATA & IDE disk.