How to choose a power supply for a computer

1. Decide on the form factor

be quiet! System Power 9 in ATX form factor

The form factor is the standardized size of the power supply unit (PSU), which must be selected for the dimensions of the computer case. The manufacturers of the latter indicate which PSUs they are compatible with. The most popular options are:

  • ATX is the most common size for PC power supplies. These have dimensions of 150 × 86 mm in height and width. The length can vary from 140 to 220 mm. This type fits most Midi-Tower and Full-Tower cases.
  • SFX are compact blocks with dimensions of 125 x 63.5 x 100 mm. This is a form factor for compact computers.
  • TFX is another form factor for smaller 85 x 64 x 175mm cases. If SFX is closer in appearance to a cube, then TFX has a more elongated shape.

In addition to the above, there are other, less common formats: EPS, FlexATX, CFX, LFX. There are also external power supplies that are not suitable for installation in classic PCs, but may be needed, for example, for single-board systems such as Raspberry Pi .

Which power supply to buy

2. Choose the right power level

Deepcool PQ1000M 1000W power supply

The power level indicates how much load the block can take on. It is better to choose a model with a margin so that the equipment does not work at the limit all the time. But too much power will be a waste of money.

The most active power supply loads the central processor and video card . To this, you can also add consumption from drives, coolers and lighting, if any.

Power consumption of powerful video cards at maximum load can reach 300-350 W, and processors – about 250 W. If you are looking for a PSU for a gaming computer, in which the components are able to overclock their operating frequencies to higher rates, then you need to add about 200 W more to the requirements for a margin.

It is important to evaluate the consumption of components by the indicated power for the 12 V line – it accounts for most of the load. It is worth remembering that manufacturers can mark the total power of the PSU by summing up all the watts issued on different lines. For example, on the 12 V line they write “600 W”, and on the lines of 3.3 V and 5 V – “150 W”. At the same time, a power of 750 W is indicated for the device, although in practice this PSU will draw only 600 W.

Also pay attention to the allowable load on each channel in amperes. A larger indicator is preferable with the same watts for different models.

By power, power supplies can be divided into several types:

  • Low -power (400-500 W) – for home and office PCs with a video card built into the processor.
  • Mid-range (500-700W) – For gaming PCs with a separate graphics adapter.
  • Powerful (700-1000 W or more) – for systems with a high load from the processor and multiple video cards.

For components, they also indicate the TDP characteristic – thermal design power, or heat dissipation requirements. Like power, the TDP of the processor and video card is determined in watts. This indicator should be guided as an approximate level, at the same time, the actual volume of consumption is smaller.

Which power supply to buy

3. Find out about the installed connectors and cables in the kit

Thinking through the configuration of the computer, you need to identify all the main elements for installation, as well as understand whether an upgrade of this system will be required in the future. When choosing a power supply, check the availability and number of required connectors in accordance with your plan.

The standard kit should include the following items:

  • 24-pin – the main connector for connecting to the power supply of the motherboard ;
  • 4- or 8-pin (or 4 + 4 pin) – connector for powering the processor;
  • 6- or 8-pin (or 6 + 2 pin) – connector for connecting a video card;
  • 15-pin SATA – cable for powering drives;
  • 4-pin Molex – connector for fans and lights.

Connecting cables to the PSU can be non-removable, semi-modular or modular. The first option is reliable in its design and maintains good contact in the connector. But the modular unit eliminates unnecessary cables, making them easy to replace or upgrade. In a semi-modular design, several main wires are not removed, and the rest can be disconnected.

4. Explore Energy Efficiency Certification

ASUS ROG‑THOR‑1200P 80 PLUS Platinum Certified Power Supply

The sticker on the case indicates the coefficient of performance (COP) of the power supply, or its efficiency. Budget models may not have such an icon at all. Blocks of the middle and premium categories usually have the inscription 80 PLUS. The color of the sticker varies from white to platinum. These labels also indicate the levels with the words: Bronze, Silver, Gold, Platinum, Titanium.

The 80 PLUS certificate shows that the equipment has a high efficiency (from 80%) and complies with modern energy consumption standards. The higher the level, the more efficient the equipment. For example, a PSU with a Titanium level has an efficiency of 92-96%.

Some power supplies also have good efficiency, but are not labeled 80 PLUS. Manufacturers in this case save on certification, although their models may not be inferior to devices with stickers in terms of parameters.

Efficient PSUs are resistant to overheating and operate quite quietly. For home use, a block with a level up to 80 PLUS Gold is enough. And Platinum and Titanium are more often installed in powerful workstations and server systems.

Which power supply to buy

5. Understand the type of cooling

Seasonic PRIME 600 power supply with passive cooling system

It depends on the cooling system how much the power supply makes noise during operation. Structures are divided into several types:

  • Passive – a silent system that uses a radiator to remove heat. It can be quite expensive compared to other options.
  • Semi -passive – in it the cooler turns on only at high loads and strong heat. This is the most common option with an optimal ratio of efficiency and price.
  • Active – here the fan runs constantly. Reliably protects from overheating, but may be too noisy for home use.

A larger diameter cooler is usually able to move more air at lower RPMs and also make less noise. But this is not always the case – the efficiency depends on the settings laid down by the manufacturer.

If the type of bearings is specified for the fan in the PSU, then it is preferable to choose hydrodynamic bearings. Compared to plain and rolling bearings, they are more reliable and quieter, although they are more expensive.

Which power supply to buy

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