What is a PSU? How should I choose a PSU?

PSU is an important part of a computer. However, not everyone is knowledgeable and knows how to choose a PSU to suit their needs. So what is a PSU? Understanding that, TipsMake will provide you with the most general and detailed information about PSUs. Let's get started right away.

What is a PSU?

PSU is the abbreviation for Power Supply Unit , which in Vietnamese means computer source. This is a piece of hardware in the computer that is responsible for converting external AC current into DC according to the battery terminals to provide energy for other parts and components.

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It can be said that, without a PSU, the computer will certainly not be able to operate. In addition, the quality of the PSU also affects the durability and stability of the computer. Therefore, when building a PC, users need to understand the characteristics and features of PSUs to make the most optimal choice.

Currently, computer sources include two main types: linear sources and nonlinear sources . In particular, the linear source will be composed of a transformer with primary and secondary coils, the output voltage will depend on the input voltage. Nonlinear sources are less dependent on the input voltage (within a certain limit) and give a fairly stable output voltage.

Function of computer source

Thus, the PSU computer power source plays an extremely important role, without it, your device will certainly not be able to operate. Specifically, the PSU will provide power for other components and devices. Thereby ensuring the stable operation of those components and devices and helping the computer operate.

What is the operating principle of PSU?

The PSU computer source will operate according to the following principle:

Starting from household electrical current (AC alternating current has 110Vac/220Vac , alternating frequency is 50/60Hz ) going to the computer source. There, the circuits will filter out high-frequency noise and then convert them into a DC voltage. Next, the DC current continues to change into alternating current, but with a lower frequency and continues to be converted into DC current. Finally, that current will be supplied to the parts and components with the appropriate voltage level so that they have energy and operate stably.

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In short, the operating principle diagram will be as follows:

Alternating current => Converted into 1-way current => Converted into bi-directional current with lower frequency => Converted into 1-way current => Distributed to components with appropriate voltage levels.

The reason we need a PSU is because the computer's parts all use unidirectional current, but the normal current we use is bidirectional current. Thus, the main effect of the PSU will be to convert 2-way current into 1-way current suitable for the voltage level of each different part. 

What is the formula for calculating PSU capacity?

PSU capacity will be calculated according to the following formula:

Watt (W) = Voltage (V) x Ampere (A)

In there:

1. Watt (W): PSU capacity.
2. Voltage (V): Voltage difference.
3. Ampere (A): Current intensity.

Parameters to note about PSU

Below are some parameters related to PSU that you need to pay attention to when learning about computer power:

PSU computer power output connections

The PSU computer power supply socket-output connections will include:

Motherboard connector

Also known as the motherboard connector, it will usually have about 20 - 24 pins (depending on the type of motherboard, the number of pins will also vary). To maximize convenience of use, manufacturers have created a 20 + 4 connector, which is a type of connector that fits both 20-pin and 24-pin boards. 

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CPU header

There are usually two main types : 4-pin type used on older motherboards and 8-pin type commonly found on newer motherboards.

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Connecting wire

This part will be color coded with specific regulations. There are usually 3 main types of plug wires: Red wire has current + 5V; The yellow wire has +12V current and the black wire will be the ground wire.

The three types of wires mentioned above will be grouped into a few common plug types as follows:

1. Molex : This is a type of connector used to connect to hard drives, optical drives and some devices such as video cards and older motherboards.
2. SATA drive connector : There are 2 to 4 flat-shaped connection ports, used to connect to SATA drives.
3. Main power supply : Includes 20-pin plug type and 24-pin plug type.
4. 12V auxiliary power cord : Includes 2 ground pins, 2 12V pins, a total of 4 plugs.
5. PCIe connector : Used to provide power to PCIe-compliant expandable memory devices. This is an extremely important plug type of this power supply.
6. 12V 8-pin EPS plug : This plug is often used for workstation motherboards and usually only appears on high-end, professional computers.
7. Floppy drive connector : Usually used for floppy drives or expansion cards with a structure of 2 ground wires, 1 5V wire and 1 +12V wire.

Wiring convention on PSU computer power supply

When learning about PSUs, you cannot help but know the general conventions that regulate voltage through the internal wire color of the computer power source as shown in the table below:

What is the PSU capacity convention?

PSU computer power capacity will be calculated depending on the supply capacity, consumption capacity, maximum capacity. In which:

Power Consumption

Power consumption is calculated by the power consumed by the computer compared to the household power source, with the unit being W. From the power consumption, users can deduce the amount of money they have to pay for the electricity they used.

Supply capacity

Power supply is calculated by the total power that the source has provided to components including: CPU, motherboard and related devices. Accordingly, the power supply capacity will depend on frequency, usage time and device characteristics. At the same time, the supplied power is always smaller than the maximum power of the computer source.

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The supplied capacity is not always the same, but there will be differences based on each time and working mode. Specifically, devices that affect power consumption will include:

1. CPU : Depending on the time such as when working less, when working at maximum and when decelerating, the CPU will consume different amounts of energy.
2. VGA graphics card : If the computer handles heavy tasks such as gaming or graphic design or video editing, the energy consumption will be greater and the capacity will also be higher than usual.
3. Northbridge chipset : On the motherboard, the northbridge chipset is considered the part that consumes the most power.
4. Optical drive : This part consumes a lot of space when having to read and write data continuously during computer operation.
5. Computer fan : Depending on the system temperature, the fan will work a lot or not. If the machine is used with high frequency and has to load many heavy programs, the temperature will increase, and the fan will have to work more than usual.

Instant peak power

This is the capacity that the power supply can achieve in a short time of about a few milliseconds (ms). This index will usually be printed and pasted by the company on the product label.

Continuous peak power

Continuous peak power is the maximum power level that a computer power supply can achieve in a state of continuous, non-stop operation for many hours or days in a row. This is a very important parameter, directly determining the smoothness and stability of a product. Therefore, you should pay attention to this parameter when looking to buy a computer.

However, you should not use the computer for a long time with continuous frequency to reach this capacity level. Because it will bring negative effects to your computer.

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How should I choose a PSU?

On the market today, there are too many brands providing different computer sources. This brings a variety of choices, but at the same time makes users confused. If you are in the same situation, please refer to the factors below to choose the most suitable product.

Wattage

Based on your needs and purpose of use, choose the PSU with the most suitable capacity. You should not be greedy for a PSU computer power supply with extremely high capacity, but do not take full advantage of the features and waste money. At the same time, you should not choose a type with too small capacity. It can lead to overload and damage computer components.

When buying a PSU computer power supply, you need to pay attention to some important symbols related to capacity as follows: Total Power (total power), Continuous Power (stable power) and Peak Power (peak power). ).

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Among them, total capacity and stable capacity will be of most concern. If the PSU only prints Peak Power, you need to consider more carefully before buying. The reason is because peak power will only represent the highest power that PSU can achieve in a few milliseconds.

Trademark

There are many PSU brands on the market today. Most users faced with many choices will turn to reputable brands to minimize possible risks. Here are a few prominent names that you can refer to:

1. Level 1 power supply : This is the highest level power supply. This power supply is popular for its stable quality and high-end components, usually only found in expensive models. Some famous brands using level 1 power supplies include: Silverstone, Corsair, Seasonic and Antec,.

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1. Level 2 power supply : This is a mid-range power supply, quite affordable. Although it does not use high-end components like the level 1 power supply, the level 2 power supply still provides quite stable capacity and has quality assurance. Cooler Master, FSP, Acbel and Thermaltake are some brands that you can refer to with this power supply. 

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1. Level 3 power supply : This is a low-range power supply that only meets ATX standards. This power supply often uses cheap components to minimize costs. Therefore, the price will be low but the quality will also decrease. Speaking of level 3 power supplies, we can mention brands such as: Huntkey, Arrow and Golden Field.

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1. Level 4 power supply : Level 4 power supply is extremely cheap. This is a low-end power supply and it can destroy your computer if you persist in using it. This type of power supply does not have a name but is often referred to as ATX.

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Besides, you can also consider whether the power supply is of good quality or not through the following factors:

1. Output voltage stability : You need to ensure that the output voltage does not differ by more than -5/+5 from the nominal voltage. In particular, the output voltage must be flat and free of noise.
2. Output power and input power must be above 80% to ensure maximum device performance.
3. The power supply does not cause magnetic or electric fields, and must also withstand magnetic interference and magnetic fields from surrounding objects.
4. The PSU computer power supply operates smoothly, without vibration, making noise or radiating too much heat during operation.
5. There are diverse sets of wires and many pins. At the same time, the connecting wires must be wrapped neatly and beautifully.
6. The initial voltage range should be between 90 - 260Vac with a frequency of about 50/60Hz.

Price

When you intend to buy a computer, you should consider your budget and spend 10 - 15% of the total cost to invest in a PSU power supply. If you buy a 20 million VND PC system, you need to spend at least 2 million VND to buy a quality power supply.

Cables can be used as separate or integral types

High-end PSU lines will often be designed with separate cables to optimize user convenience. Thus, when it feels cumbersome and no longer needed, users can easily remove it and store it away. This also helps the computer storage space become neater and more beautiful, while also increasing air circulation.

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If you intend to buy a mid-level power supply, my advice is to choose PSUs with semi-fixed and semi-removable cables. Then, except for the fixed 8-pin CPU and 24-pin ATX, you can detach all other cables when you want.

Particularly with low-level power supplies, the components are often fixed inside to optimize costs to the lowest level. However, you should choose one with a filter inside to increase air circulation while still ensuring neatness and beauty.

Epilogue

Thus, the above article has answered the question of what a PSU is for most people who are new to computers and want to build their own system. This is a device that plays an extremely important and indispensable role in any system. Hope you choose a good quality PSU that meets your needs to have the most productive time working and studying on your computer.

Jessica Tanner

Update 03 October 2023