How to calculate PSU (power supply unit) wattage for the PC?

Converting the AC voltage coming from the electric network into a permanent one, powering computer components and ensuring that the power is always at the required level – these are the tasks of the power supply unit (PSU). Assembling your (PC) computer and updating it’s components, you should take a good look at the power supply unit (PSU), that will serve them all: graphic card, processor, motherboard and other elements. After you read this article, you will be able to choose the correct power supply for your computer all by yourself.

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Table of contents:
1. How is the PSU wattage calculated
2. PSU calculation services
- Extreme power supply calculator
- MSI power supply calculator

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How is the PSU wattage calculated

To correctly choose the power supply unit (PSU), which is needed for your particular computer (PC), you will need to collect all data on the energy consumption of each individual component of the system. Of course, some users may decide to buy a power supply unit (PSU) with maximum wattage, and this is really an effective way to not make a mistake, but it’s very expensive. The price for a 800-1000 watt power supply unit (PSU) may be 2-3 times higher than the price for a 400-500 watts PSU, but sometimes the latter one will be quite enough for the selected components of your computer.

While collecting components for their computers in the store, some buyers decide to ask a sales consultant for advice. This is not the best way, given the fact that not always and not all sellers are qualified enough.

The best option is to calculate the wattage of your power supply unit (PSU) independently. You can do it with the help of special websites and it’s quite simple, but this will be discussed below. Now we propose to get acquainted with some general information about the power consumption of each computer component:

• Motherboard. Its power consumption depends on the number of installed functions. In case the motherboard manufacturer has built a graphic card, sound card, coolers and other components into it, its power consumption will be higher. An average motherboard needs from 20 to 35 watts;
• CPU. The power consumption of any CPU depends on its performance. Processors with 2 cores at a low frequency consume significantly less than powerful 8 core ones. By allocating the averaged figures, it can be noted that the CPU power consumption ranges from 50 to 150 watts;
• Graphic card. It is the most complex component of any computer in terms of wattage calculating. Graphic card consumption varies depending on its power. It is possible to determine the average power required for the graphic card operation in the range from 100 to 300 watts;
• HDD (Hard Drive). Hard drive characteristics are also affecting the required PSU wattage, just like the performance of other components of the system. On average, one hard drive (HDD) requires from 20 to 60 watts;
• Sound card. If the sound card is not built-in but installed in the (PC) computer separately, it may require up to 50 watts of extra power from the power supply unit (PSU);
• DVD-drive. In the “sleeping” mode, the drive oriented to work with DVDs requires up to 15 watts. When the DVD-drive is working and spinning the disk, its consumption depends on the rotation speed. Usually, the load on the DVD drive requires no more than 25 watts of energy.

Above we have listed the main PC components, which you will have to keep in mind calculating wattage for your PSU. Please note that there must be added extra 50-100 watts that will go for the operation of coolers, keyboard, mouse, various accessories and a “stock” for the proper system operation under significant load.

PSU calculation services

It is not always easy to find information on the wattage required for this or another computer component online.  In this regard, the process of independent PSU wattage calculation may take a lot of time and effort. But there are some special online services that allow you to calculate the wattage consumed by the PC components and suggest the optimal PSU option for your computer.

Extreme power supply calculator

One of the best online PSU wattage calculators. Among its main advantages are a convenient interface and a huge components database. In addition, this service allows you to calculate not only the “basic” power consumption, but also the higher one, which is typical when the processor or graphics card is overclocked. This service can calculate the required SPU wattage using simplified or expert settings. The extended version allows you to specify the parameters of PC components and select the mode of operation for your future computer.

MSI power supply calculator

This well-known company – MSI – is manufacturing gaming components for computers, and it has a PSU calculator on its website. When you select each component of the system, MSI calculator will show you how much the required PSU wattage varies in this or another case. Also, the full localization of the calculator can be considered a clear advantage. However, using the service from MSI, it should be remembered that the power supply unit should be purchased with wattage that is 50-100 watts higher than the MSI calculator recommends, since this service when calculating does not take into account the keyboard, mouse and some other additional accessories power consumption.