7 Things to Consider Before Buying Power Supply for Your Computer

How to choose power supply

While the purchase of a computer power supply is very often ignored, the importance of this component cannot be emphasized enough. Truth is, the PC power supplies are no less important than the CPU, graphics card, or hard drive.

If the choice of power supply is not appropriate, you might end up with low power, which is not sufficient to run all the PC’s hardware and software. Similarly, you might end up with heavy power, which could potentially burn computer components.

When it comes to how to choose a power supply, a lot of considerations ought to be put on quality. You don’t want to end up with too little or too much power for your PC. To avoid power supply-related mishaps, a careful analysis of the computer hardware and software power capacities is imperative.

Having said that, let us take a look at some of the aspects to consider when choosing your power supply unit. In order to get some context, let’s begin with a quick definition of power supply.

What is Power Supply?

Power Supply

A Power Supply, also referred to as Power Supply Unit (PSU), is a computer hardware component used to convert alternating current (AC) to direct current (DC). Meaning from the mains input power of 210V, 240, or 250V AC, the power supply converts it into 5V, -5V, +12V, -12V, +3.3V, or -3.3V DC, which is then used to power the hardware components of the PC.

How to buy a power supply comes down to a set of factors. Below are some of the things to look for when shopping for your power supply.

1. The Power Supply Sizes

The Power Supply Sizes

There are two main types; ATX and SFX.

ATX power supplies have the following specs:

  • Size: Standard
  • Dimensions: 150 x 140 x 86 mm
  • Tip! General ATX power supply can be used both on ATX and MTX motherboards. This is because the reserved space on both types of chassis is enough for this PSU.

SFX power supply has the following specs:

  • Size: Standard
  • Dimensions: 125 x 100 x 63.5 mm
  • Tip! The SFX power supply is generally designed for the ITX motherboard. The reason for this is because the body of SFX is comparatively smaller than that of the ATX power supply. Also, its output wattage is lower.

2. Power Supply Module

Power Supply Module

The power supply module is broadly classified into two main classes:

i). According to whether or not the wires are removable.

ii). According to support for future upgrade

  • Classification According to Whether or not the Wires are Removable

Under this category, power supply units are classified into three main modules. These include:

  • Full module: This module allows for the disassembling and replacement of wires according to the user’s preference.
  • Half module: In this power supply module, some parts of the cable can be removed. Note, however, that the motherboard and CPU’s power supply lines cannot be removed.
  • Non-module: This power supply module has all the cables attached to its host components and cannot be removed at all. Moreover, it has no room for any additional plugs.
  • Classification According to Support for Future Upgrade

Here, we consider the likelihood of future hardware upgrades for the power supply unit. Meaning you need to look for a PSU that has replaceable components. That makes for easy component replacement or PSU upgrade in case of damage.

3. The Number of Power Connections

Number of Power Connections

The number of power connections is also a very important aspect that you need to consider when shopping for an ideal PSU. Generally, the number of mainboard power supply is 24-pin (20+4) while that of the CPU and the GPU is 8-PIN (4+4) and 8-pin (4+6), respectively.

It is also worth noting that you will need to look at the number of the D-type and SATA interfaces in case you plan to increase the number of graphics cards or SATA hard drives at some point. That way, you will be able to reserve some power ports.

4. The 80 PLUS

The 80 PLUS

80 PLUS basically refers to how efficient the power supply is when converting the AC to DC. This is important to note because there is always some power that is lost during the conversion process. With that in mind, 80 PLUS has a table that shows the efficiency in terms of certification levels. It is arranged in such a way that values further to the right indicate more efficient conversion rates. The converse is also true.

The 80 PLUS consists of power supplies that have been tested independently and rated in terms of power output, efficiency, and load capacities. It is divided into four levels as per these rates. These levels include the 80 PLUS, 80 PLUS Bronze, 80 PLUS Silver, and 80 PLUS Gold.

Something else to remember is that 80 PLUS is not representative of the quality of the power supply. From the cost performance point of view, the 80 PLUS Bronze medal is usually preferred owing to its affordability and performance.

5. Calculation of Power Consumption

computers power consumption

A computer's power consumption is the sum total of the amount of power its hardware components required to operate efficiently. The most common power consumption rates are 450W, 500W, 650W, 750W, and 850W.

As we had mentioned earlier, your choice power supply should be capable of sustaining all the components of your device. The most important of this hardware are the motherboard, graphics cards, CPU, memory, and cooling fan. You need to calculate the total power consumption of all these components before deciding on the particular type of power supply for your computer.

We’ve put together a chart of CPU and graphics card power consumption rates. You can use the chart to get an estimated value for your system’s power consumption and use that knowledge to purchase the right power supply unit.

Calculation of Power Consumption

Because of the overwhelming number of motherboards, fans, and other PC hardware in the market today, choosing the right power supply can be a bit of a challenge. This is especially true because hardware components from different manufacturers may have different power ratings. Be that as it may, we suggest that you increment your calculated CPU and graphics card power consumption values by about 100W directly. That’s to say:

Total power supply = CPU power + GPU power + 100 Watts.

Online Estimate

Instead of relying on guesswork and approximation of power consumption values, there are reputable websites that can help you get a near-accurate power consumption rate for your PC’s hardware components.

Here’s one such website that allows you to choose your hardware online and estimate the power in watts. Also noteworthy is that if you intend to overclock your PC, be sure to factor in the wattage (watts of power) for overclocking when computing the total power output for your power supply unit. Usually, overclocking consumes about 30% of the CPU and graphic cards power.

6. Security and Protection

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  • Daily Maintenance of the Power Supply

To keep power supplies in good shape, a number of interventions can go a long way. Here are some daily maintenance tips for your power supply:

  • Set your PC in a clean and dust-free surrounding.
  • Clean dirt, dust, and grime that might have accumulated on the power supply unit
  • Avoid overloading the power supply. Excess power will damage the PSU.
  • One in a while, have a technician check the unit’s input and output current and voltage just to be sure it’s working properly.

7. Power Supply Brand Recommendations

Power Supply Brand Recommendations

Power Supplies are broadly classified into:

i). First Class Brands

ii). Second Class Brands

  • First Class Brands

Some of the priority PSU brands include:

  • Seasonic

Seasonic is a leading manufacturer and retailer of high-grade power supply units. The company is based in Taiwan.

  • Delta

Delta deals in standard single-phase power supply units with a broad operating temperature range of between -20°C and +70°C.

  • Corsair

Corsair power supplies incorporate the logical link control resonant topology to improve system power consumption efficiency at lower loads.

  • Antec

Antec is a Taiwanese company specializing in the manufacture of PC cases and high-quality PSUs.

  • Super Flower

A leading PSU OEM that makes power supply units for companies like EVGA. It’s one of the latest entrants in the North American PSU market.

  • Second Class Brands

Common PSU brands in this category include:

  • Great Wall
  • Huntkey
  • CoolerMaster


1. Does a higher power supply consume more power?

No. The power consumption of your power supply is solely dependent on the amount of power that your hardware consumes. However, the power supplies with high powers are usually more expensive than the standard ones. Hence you just need to know which power supply works best for you according to your power consumption needs, as shown in the power calculation formula above.

2. Is it better to have a higher watt power supply?

Yes. It is better to have a higher wattage PSU that can be operated at half capacity than try to run a low wattage power supply at full capacity.

3. What power supply unit is good for gaming?

Gaming PCs with mid to high-end graphics are better served with power supplies with an output range of between 650W and 850W. Simply put, most gamers should get by with a 750W PSU. If you plan on overclocking, then you’ll definitely need a higher capacity power supply.

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